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Water, Volume 9, Issue 2 (February 2017)

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Cover Story Clogging due to the accumulation of suspended solids is a major constraint that limits the capacity [...] Read more.
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Editorial

Jump to: Research, Review

Open AccessEditorial Lake Restoration and Management in a Climate Change Perspective: An Introduction
Water 2017, 9(2), 122; doi:10.3390/w9020122
Received: 20 December 2016 / Accepted: 3 February 2017 / Published: 14 February 2017
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Abstract
Lakes all around the globe are under severe pressure due to an increasing anthropogenic impact from a growing population in a more developed world. Accordingly, today, many lakes are highly eutrophic and suffer from severe blooms of often toxic cyanobacteria and may become
[...] Read more.
Lakes all around the globe are under severe pressure due to an increasing anthropogenic impact from a growing population in a more developed world. Accordingly, today, many lakes are highly eutrophic and suffer from severe blooms of often toxic cyanobacteria and may become even more eutrophic in the future unless strong lake management actions are taken. Recent research has further shown that global warming and subsequent changes in water use will further exacerbate the eutrophication process in lakes. There is therefore a growing demand for lake restoration and insight into sustainable lake management. The measures to be taken, however, depend on the climate and other local conditions. This special issue addresses lake restoration and management with special emphasis on the restoration of eutrophicated lakes within a climate change perspective. The papers included collectively highlight that the ongoing climate change affects lake water quality by (1) changes in external and internal nutrient loading; (2) higher frequency of extreme events (such as hurricanes); (3) temperature‐induced changes in biota, biotic interactions; and (4) water level. Lower nutrient loading is therefore needed in a future warmer world to achieve the same ecological state as today. Several papers discuss lake restoration methods within a climate change perspective and show practical results, notably of various attempts of biomanipulation. Finally, some papers discuss the effects of other anthropogenic stressors and their interaction with climate. Full article
(This article belongs to the Special Issue Lake Restoration and Management in a Climate Change Perspective)

Research

Jump to: Editorial, Review

Open AccessArticle Comparison of Multi-Criteria Decision Support Methods for Integrated Rehabilitation Prioritization
Water 2017, 9(2), 68; doi:10.3390/w9020068
Received: 24 October 2016 / Revised: 20 December 2016 / Accepted: 17 January 2017 / Published: 24 January 2017
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Abstract
The decisions taken in rehabilitation planning for the urban water networks will have a long lasting impact on the functionality and quality of future services provided by urban infrastructure. These decisions can be assisted by different approaches ranging from linear depreciation for estimating
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The decisions taken in rehabilitation planning for the urban water networks will have a long lasting impact on the functionality and quality of future services provided by urban infrastructure. These decisions can be assisted by different approaches ranging from linear depreciation for estimating the economic value of the network over using a deterioration model to assess the probability of failure or the technical service life to sophisticated multi-criteria decision support systems. Subsequently, the aim of this paper is to compare five available multi-criteria decision-making (MCDM) methods (ELECTRE, AHP, WSM, TOPSIS, and PROMETHEE) for the application in an integrated rehabilitation management scheme for a real world case study and analyze them with respect to their suitability to be used in integrated asset management of water systems. The results of the different methods are not equal. This occurs because the chosen score scales, weights and the resulting distributions of the scores within the criteria do not have the same impact on all the methods. Independently of the method used, the decision maker must be familiar with its strengths but also weaknesses. Therefore, in some cases, it would be rational to use one of the simplest methods. However, to check for consistency and increase the reliability of the results, the application of several methods is encouraged. Full article
(This article belongs to the Special Issue Synergies in Urban Water Infrastructure Modeling)
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Open AccessArticle Integrating Local Scale Drainage Measures in Meso Scale Catchment Modelling
Water 2017, 9(2), 71; doi:10.3390/w9020071
Received: 12 September 2016 / Revised: 23 December 2016 / Accepted: 30 December 2016 / Published: 25 January 2017
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Abstract
This article presents a methodology to optimize the integration of local scale drainage measures in catchment modelling. The methodology enables to zoom into the processes (physically, spatially and temporally) where detailed physical based computation is required and to zoom out where lumped conceptualized
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This article presents a methodology to optimize the integration of local scale drainage measures in catchment modelling. The methodology enables to zoom into the processes (physically, spatially and temporally) where detailed physical based computation is required and to zoom out where lumped conceptualized approaches are applied. It allows the definition of parameters and computation procedures on different spatial and temporal scales. Three methods are developed to integrate features of local scale drainage measures in catchment modelling: (1) different types of local drainage measures are spatially integrated in catchment modelling by a data mapping; (2) interlinked drainage features between data objects are enabled on the meso, local and micro scale; (3) a method for modelling multiple interlinked layers on the micro scale is developed. For the computation of flow routing on the meso scale, the results of the local scale measures are aggregated according to their contributing inlet in the network structure. The implementation of the methods is realized in a semi-distributed rainfall-runoff model. The implemented micro scale approach is validated with a laboratory physical model to confirm the credibility of the model. A study of a river catchment of 88 km2 illustrated the applicability of the model on the regional scale. Full article
(This article belongs to the Special Issue Hydroinformatics and Urban Water Systems)
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Open AccessArticle Including A-Priori Assessment of Actual Evapotranspiration for Green Roof Daily Scale Hydrological Modelling
Water 2017, 9(2), 72; doi:10.3390/w9020072
Received: 25 October 2016 / Revised: 3 January 2017 / Accepted: 16 January 2017 / Published: 24 January 2017
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Abstract
In the last decades, there has been a widespread implementation of Green Infrastructures worldwide. Among these, green roofs appear to be particularly flexible sustainable drainage facilities. To predict their effectiveness for planning purposes, a tool is required that provides information as a function
[...] Read more.
In the last decades, there has been a widespread implementation of Green Infrastructures worldwide. Among these, green roofs appear to be particularly flexible sustainable drainage facilities. To predict their effectiveness for planning purposes, a tool is required that provides information as a function of local meteorological variables. Thus, a relatively simple daily scale, one-dimensional water balance approach has been proposed. The crucial evapotranspiration process, usually considered as a water balance dependent variable, is replaced here by empirical relationships providing an a-priori assessment of soil water losses through actual evapotranspiration. The modelling scheme, which under some simplification can be used without a calibration process, has been applied to experimental runoff data monitored at a green roof located near Bernkastel (Germany), between April 2005 and December 2006. Two different empirical relationships have been used to model actual evapotranspiration, considering a water availability limited and an energy limited scheme. Model errors quantification, ranging from 2% to 40% on the long-term scale and from 1% to 36% at the event scale, appear strongly related to the particularly considered relationship. Full article
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Open AccessArticle The Use of Stable Water Isotopes as Tracers in Soil Aquifer Treatment (SAT) and in Regional Water Systems
Water 2017, 9(2), 73; doi:10.3390/w9020073
Received: 31 October 2016 / Revised: 10 January 2017 / Accepted: 12 January 2017 / Published: 24 January 2017
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Abstract
This study examines the feasibility of tracing and quantifying the progress of different water sources along the water–effluent–SAT (Soil Aquifer Treatment) chain using 2H and 18O isotopes. The research was conducted at the Dan Region Reclamation Plant (Shafdan), which reclaims ~135
[...] Read more.
This study examines the feasibility of tracing and quantifying the progress of different water sources along the water–effluent–SAT (Soil Aquifer Treatment) chain using 2H and 18O isotopes. The research was conducted at the Dan Region Reclamation Plant (Shafdan), which reclaims ~135 MCM/year of effluent for irrigation. Water samples representing different stages along the chain were taken in two surveys during 2010–2011 and 2014. δ18O and δ2H values were used for mixing ratios (MR) calculations, and compared with calculated MRs using chloride and carbamazepine concentrations. The results showed a relative enrichment of 18O and 2H in the Israeli water system compared to the regional groundwater, due to the addition of massive quantities of desalinated water. A linear correlation for δ2H vs. δ18O with a slope of 4.5 was found for the different freshwater sources and their mixing products, suggesting evaporation-mixing effects. MR values indicate on the spreading of new type of effluent originating from desalinated water in the aquifer. A dilution model explains the isotopic compositions in the water system and of the Shafdan effluents. Water isotopes have an advantage over other tracers, due to the ability to predict their ratio in the supply system and in the effluent, based on mass balance calculations and on knowledge of water supply volumes. Full article
(This article belongs to the Special Issue Water Quality Considerations for Managed Aquifer Recharge Systems)
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Open AccessArticle Multi-Model Grand Ensemble Hydrologic Forecasting in the Fu River Basin Using Bayesian Model Averaging
Water 2017, 9(2), 74; doi:10.3390/w9020074
Received: 14 November 2016 / Revised: 24 December 2016 / Accepted: 17 January 2017 / Published: 24 January 2017
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Abstract
Statistical post-processing for multi-model grand ensemble (GE) hydrologic predictions is necessary, in order to achieve more accurate and reliable probabilistic forecasts. This paper presents a case study which applies Bayesian model averaging (BMA) to statistically post-process raw GE runoff forecasts in the Fu
[...] Read more.
Statistical post-processing for multi-model grand ensemble (GE) hydrologic predictions is necessary, in order to achieve more accurate and reliable probabilistic forecasts. This paper presents a case study which applies Bayesian model averaging (BMA) to statistically post-process raw GE runoff forecasts in the Fu River basin in China, at lead times ranging from 6 to 120 h. The raw forecasts were generated by running the Xinanjiang hydrologic model with ensemble forecasts (164 forecast members), using seven different “THORPEX Interactive Grand Global Ensemble” (TIGGE) weather centres as forcing inputs. Some measures, such as data transformation and high-dimensional optimization, were included in the experiment after considering the practical water regime and data conditions. The results indicate that the BMA post-processing method is capable of improving the performance of raw GE runoff forecasts, yielding more calibrated and sharp predictive probability density functions (PDFs), over a range of lead times from 24 to 120 h. The analysis of percentile forecasts in two different flood events illustrates the great potential and prospects of BMA GE probabilistic river discharge forecasts, for taking precautions against severe flooding events. Full article
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Open AccessArticle Determination of the Geogenic Metal Background in Surface Water: Benchmarking Methodology for the Rivers of Saxony-Anhalt, Germany
Water 2017, 9(2), 75; doi:10.3390/w9020075
Received: 29 September 2016 / Revised: 13 January 2017 / Accepted: 19 January 2017 / Published: 25 January 2017
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Abstract
Geogenic concentrations are defined as those concentrations that represent the natural background without any anthropogenic influence. The paper describes a statistical method for determining geogenic metal concentrations in rivers based on the concept of “aggregated riverine landscapes” (ARLs), which applies to all rivers
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Geogenic concentrations are defined as those concentrations that represent the natural background without any anthropogenic influence. The paper describes a statistical method for determining geogenic metal concentrations in rivers based on the concept of “aggregated riverine landscapes” (ARLs), which applies to all rivers in the Federal State of Saxony-Anhalt (Germany). The methodology includes the pre-selection of existing data by eliminating all sampling locations from the database which have anthropogenic influence, the GIS-based allocation of the sampling locations with respect to the respective ARL being the evaluation units, and the assessment of the geogenic background by statistical calculation of the 90th percentile. After validation of the methodology, the existing database was complemented by additional measurements for regions with data gaps. About 85,000 records of water samples, 1400 records of sediment samples, and 920 records of suspended particulate samples were used for the determination of the geogenic metal concentrations in the rivers of Saxony-Anhalt. The investigation included the parameters Al, Ag, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Ti, U, V, and Zn. The investigation results offer the determination of regions with increased background levels for certain metals or metalloids in Saxony-Anhalt. Full article
(This article belongs to the Special Issue Water Quality and Health)
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Open AccessArticle Assessment of Optional Sediment Transport Functions via the Complex Watershed Simulation Model SWAT
Water 2017, 9(2), 76; doi:10.3390/w9020076
Received: 3 October 2016 / Revised: 13 January 2017 / Accepted: 18 January 2017 / Published: 29 January 2017
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Abstract
The Soil and Water Assessment Tool 2012 (SWAT2012) offers four sediment routing methods as optional alternatives to the default simplified Bagnold method. Previous studies compared only one of these alternative sediment routing methods with the default method. The proposed study evaluated the impacts
[...] Read more.
The Soil and Water Assessment Tool 2012 (SWAT2012) offers four sediment routing methods as optional alternatives to the default simplified Bagnold method. Previous studies compared only one of these alternative sediment routing methods with the default method. The proposed study evaluated the impacts of all four alternative sediment transport methods on sediment predictions: the modified Bagnold equation, the Kodoatie equation, the Molinas and Wu equation, and the Yang equation. The Arroyo Colorado Watershed, Texas, USA, was first calibrated for daily flow. The sediment parameters were then calibrated to monthly sediment loads, using each of the four sediment routing equations. An automatic calibration tool—Integrated Parameter Estimation and Uncertainty Analysis Tool (IPEAT)—was used to fit model parameters. The four sediment routing equations yielded substantially different sediment sources and sinks. The Yang equation performed best, followed by Kodoatie, Bagnold, and Molinas and Wu equations, according to greater model goodness-of-fit (represented by higher Nash–Sutcliffe Efficiency coefficient and percent bias closer to 0) as well as lower model uncertainty (represented by inclusion of observed data within 95% confidence interval). Since the default method (Bagnold) does not guarantee the best results, modelers should carefully evaluate the selection of alternative methods before conducting relevant studies or engineering projects. Full article
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Open AccessArticle Robust Initial Wetness Condition Framework of an Event-Based Rainfall–Runoff Model Using Remotely Sensed Soil Moisture
Water 2017, 9(2), 77; doi:10.3390/w9020077
Received: 31 October 2016 / Revised: 10 January 2017 / Accepted: 12 January 2017 / Published: 27 January 2017
Cited by 2 | PDF Full-text (3741 KB) | HTML Full-text | XML Full-text
Abstract
Runoff prediction in limited-data areas is vital for hydrological applications, such as the design of infrastructure and flood defenses, runoff forecasting, and water management. Rainfall–runoff models may be useful for simulation of runoff generation, particularly event-based models, which offer a practical modeling scheme
[...] Read more.
Runoff prediction in limited-data areas is vital for hydrological applications, such as the design of infrastructure and flood defenses, runoff forecasting, and water management. Rainfall–runoff models may be useful for simulation of runoff generation, particularly event-based models, which offer a practical modeling scheme because of their simplicity. However, there is a need to reduce the uncertainties related to the estimation of the initial wetness condition (IWC) prior to a rainfall event. Soil moisture is one of the most important variables in rainfall–runoff modeling, and remotely sensed soil moisture is recognized as an effective way to improve the accuracy of runoff prediction. In this study, the IWC was evaluated based on remotely sensed soil moisture by using the Soil Conservation Service-Curve Number (SCS-CN) method, which is one of the representative event-based models used for reducing the uncertainty of runoff prediction. Four proxy variables for the IWC were determined from the measurements of total rainfall depth (API5), ground-based soil moisture (SSMinsitu), remotely sensed surface soil moisture (SSM), and soil water index (SWI) provided by the advanced scatterometer (ASCAT). To obtain a robust IWC framework, this study consists of two main parts: the validation of remotely sensed soil moisture, and the evaluation of runoff prediction using four proxy variables with a set of rainfall–runoff events in the East Asian monsoon region. The results showed an acceptable agreement between remotely sensed soil moisture (SSM and SWI) and ground based soil moisture data (SSMinsitu). In the proxy variable analysis, the SWI indicated the optimal value among the proposed proxy variables. In the runoff prediction analysis considering various infiltration conditions, the SSM and SWI proxy variables significantly reduced the runoff prediction error as compared with API5 by 60% and 66%, respectively. Moreover, the proposed IWC framework with remotely sensed soil moisture indicates an improved Nash–Sutcliffe efficiency from 0.48 to 0.74 for the four catchments in the Korean Peninsula. It can be concluded that the SCS-CN method extended with remotely sensed soil moisture for reducing uncertainty in the runoff prediction and the proxy variables obtained from the soil moisture data provided by the ASCAT can be useful in enhancing the accuracy of runoff prediction over a range of spatial scales. Full article
(This article belongs to the Special Issue Remote Sensing of Soil Moisture)
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Open AccessArticle Spatial and Temporal Changes in Temperature, Precipitation, and Streamflow in the Miyun Reservoir Basin of China
Water 2017, 9(2), 78; doi:10.3390/w9020078
Received: 11 October 2016 / Revised: 18 January 2017 / Accepted: 19 January 2017 / Published: 28 January 2017
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Abstract
With the influence of global climate warming, the responses of regional hydroclimatic variables to climate change are of great importance for water resource planning and management. The evolution of precipitation, mean temperature, and runoff at different timescales, was investigated using the Mann–Kendall test
[...] Read more.
With the influence of global climate warming, the responses of regional hydroclimatic variables to climate change are of great importance for water resource planning and management. The evolution of precipitation, mean temperature, and runoff at different timescales, was investigated using the Mann–Kendall test from 1969 to 2011 in the Miyun Reservoir Basin, China. In addition, three precipitation indices and different precipitation grades were also considered. Annual precipitation had a non-significant decreasing trend, flood precipitation trend was significantly decreasing with a magnitude of 18.50 mm/10 years, and non-flood precipitation trend was significantly increasing with a magnitude of 6.91 mm/10 years. Precipitation frequency in flood season featured a significantly decreasing trend. Meanwhile, flood precipitation intensity for large rain (25 ≤ p < 50 mm/day) and non-flood precipitation amount for medium rain (10 ≤ p < 25mm/day) also showed significant increasing trends. The mean temperature exhibited significant upward trends during the year, in flood season, and in non-flood season with rates of 0.36 °C/10 years, 0.32 °C/10 years and 0.38 °C/10 years, respectively. The magnitude of the mean temperature increase in the non-flood season was greater than in the flood season. Runoff experienced continuous and significant downward trends of 1.6 × 108 m3/10 years, 1.1 × 108 m3/10 years and 0.40 × 108 m3/10 years, respectively, during the year, in flood season, and in non-flood season. The decreased annual streamflow was more obvious after 2000 than before. The results obtained in this study could be used as references for decision-making regarding water resource management in the watershed. Full article
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Open AccessArticle Antibiotic Resistance Profiling and Genotyping of Vancomycin-Resistant Enterococci Collected from an Urban River Basin in the Provincial City of Miyazaki, Japan
Water 2017, 9(2), 79; doi:10.3390/w9020079
Received: 6 November 2016 / Accepted: 19 January 2017 / Published: 30 January 2017
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Abstract
The distribution characteristics of vancomycin-resistant enterococci (VRE) and the resistance of enterococcus isolates to various antibiotics were investigated in Yae River, which flows through Miyazaki city, Japan. The prevalence of VRE among specimens collected from the urban river basin using mEI agar was
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The distribution characteristics of vancomycin-resistant enterococci (VRE) and the resistance of enterococcus isolates to various antibiotics were investigated in Yae River, which flows through Miyazaki city, Japan. The prevalence of VRE among specimens collected from the urban river basin using mEI agar was 0.9% (2 of 226 enterococcal isolates). In the 333 enterococcal isolates obtained using mEI agar or vancomycin-supplemented mEI agar, the possession of the vancomycin-resistant genes (vanA, vanB, vanC1, and vanC2/C3) was examined using multiplex PCR analysis. Although VRE possessing vanA and vanB were not detected in any isolates, isolates possessing vanC2/C3 were detected at all sampling sites and on all days. All isolates (101 strains) possessing vanC2/C3 that were obtained on vancomycin-supplemented mEI agar were identified as E. casseliflavus and analyzed for genotypes using pulse-field gel electrophoresis (PFGE) analysis. These E. casseliflavus isolates revealed them to be genetically highly divergent strains, suggesting that many contamination sources were present in this study area. Many of the enterococcal isolates obtained were resistant to erythromycin, ciprofloxacin, and tetracycline; enterococci distributed in the studied urban river basin are resistant to universally applicable antibiotics. These results indicate that VRE carrying vanC2/C3 are distributed in Yae River, and the sources of VRE are scattered across the river basin. Full article
(This article belongs to the Special Issue Water Quality and Health)
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Open AccessArticle Commercial Aquaponics Approaching the European Market: To Consumers’ Perceptions of Aquaponics Products in Europe
Water 2017, 9(2), 80; doi:10.3390/w9020080
Received: 1 October 2016 / Accepted: 16 January 2017 / Published: 31 January 2017
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Abstract
The first commercial aquaponics companies are starting up in Europe. The main focus has been on solving technology issues and optimizing production. However, increasing attention is now being paid to certification and regulations linked to aquaponics, as well as the marketing of products
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The first commercial aquaponics companies are starting up in Europe. The main focus has been on solving technology issues and optimizing production. However, increasing attention is now being paid to certification and regulations linked to aquaponics, as well as the marketing of products and services. The paper presents the results of a study whose main aim was to estimate consumers’ knowledge about aquaponics and their acceptance of aquaponics products in different European regions. An on-line questionnaire was administered to the general public through the aquaponics network of Food and Agriculture COST (European Cooperation in Science and Technology) Action FA1305 “The EU Aquaponics Hub—Realising Sustainable Integrated Fish and Vegetable Production for the EU” in 16 European countries. The methodology includes univariate and multivariate statistical techniques. The results show that, on average, attitudes towards aquaponics were positive, showing no significant differences between those who already knew about aquaponics and those who only heard about it through the survey. More than 50% of respondents had never heard of aquaponics, whilst more than 70% had already heard of hydroponics. No more than 17% of respondents were willing to pay more for aquaponically produced products and no more than 40% more when compared to the price of products from conventional farming. The results confirm three different clusters of potential consumers of aquaponics products. They also suggest an urgent need for implementing integrated and holistic approaches involving all stakeholders in aquaponics, in order to define a marketing plan and efficient communication strategies. This COST action, other projects and public decision makers must invest in educating consumers about aquaponics through the organization of guided tours, thematic workshops and tastings of aquaponics products in order to raise their awareness about this new technology. It is absolutely urgent that public decision makers, in cooperation with aquaponics stakeholders, address the main institutional constraints, namely the introduction of aquaponics as an economic activity and the organic certification of aquaponics products. Full article
(This article belongs to the Special Issue Aquaponics: Toward a Sustainable Water-Based Production System?)
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Open AccessArticle Extreme Precipitation Frequency Analysis Using a Minimum Density Power Divergence Estimator
Water 2017, 9(2), 81; doi:10.3390/w9020081
Received: 11 October 2016 / Accepted: 24 January 2017 / Published: 27 January 2017
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Abstract
The recently observed hydrologic extremes are unlike what has been experienced so far. Both the magnitude and frequency of extremes are important indicators that determine the flood safety design criteria. Therefore, how are design criteria updated faced with these extremes? Both a sudden
[...] Read more.
The recently observed hydrologic extremes are unlike what has been experienced so far. Both the magnitude and frequency of extremes are important indicators that determine the flood safety design criteria. Therefore, how are design criteria updated faced with these extremes? Both a sudden increase of design rainfall by the inclusion of these extremes and complete ignorance are inappropriate. In this study, the changes in extremes were examined and an alternative way to estimate the design rainfall amounts was developed using the data from 60 stations in South Korea. The minimum density power divergence estimator (MDPDE) with the optimal value of a tuning parameter, α, was suggested as an alternative estimator instead of the maximum likelihood estimator (MLE); its performance was evaluated using the Gumbel (GUM) and the generalized extreme value (GEV) distribution. The results revealed an increase in both the frequency and magnitude of extreme events over the last two decades, which imply that the extremes are already occurring. The performance of the MDPDE was evaluated. The results revealed decreased and adjusted values of the design rainfall compared to MLE. On the other hand, the MDPDE of the GEV distribution with a positive shape parameter, ξ, does not show its advantage conditionally because the GEV distribution has a heavier right tail than the GUM distribution (ξ = 0). In contrast, the results showed the high sensitivity of the MLE to the extremes compared to MDPDE. Full article
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Open AccessArticle Examining the Relationship between Drought Indices and Groundwater Levels
Water 2017, 9(2), 82; doi:10.3390/w9020082
Received: 1 October 2016 / Accepted: 19 January 2017 / Published: 27 January 2017
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Abstract
Thorough characterization of the response of finite water resources to climatic factors is essential for water monitoring and management. In this study, groundwater level data from U.S. Geological Survey Ground-Water Climate Response Network wells were used to analyze the relationship between selected drought
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Thorough characterization of the response of finite water resources to climatic factors is essential for water monitoring and management. In this study, groundwater level data from U.S. Geological Survey Ground-Water Climate Response Network wells were used to analyze the relationship between selected drought indices and groundwater level fluctuation. The drought episodes included in this study were selected using climate division level drought indices. Indices included the Palmer Drought Severity Index, Palmer Hydrological Drought Index, and Standardized Precipitation Index (SPI-6, 9, 12, 24). Precipitation and the average temperature were also used. SPI-24 was found to correlate best with groundwater levels during drought. For 17 out of 32 wells, SPI-24 showed the best correlation amongst all of the indices. For 12 out of 32 wells, SPI-24 showed correlation coefficients of −0.6 or stronger; and for other wells, reasonably good correlation was demonstrated. The statistical significance of SPI-24 in predicting groundwater level was also tested. The correlation of average monthly groundwater levels with SPI-24 does not change much throughout the timeframe, for all of the studied wells. The duration of drought also had a significant correlation with the decline of groundwater levels. This study illustrates how drought indices can be used for a rapid assessment of drought impact on groundwater level. Full article
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Open AccessArticle Water Savings of Crop Redistribution in the United States
Water 2017, 9(2), 83; doi:10.3390/w9020083
Received: 25 October 2016 / Accepted: 22 December 2016 / Published: 30 January 2017
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Abstract
Demographic growth, changes in diet, and reliance on first-generation biofuels are increasing the human demand for agricultural products, thereby enhancing the human pressure on global freshwater resources. Recent research on the food-water nexus has highlighted how some major agricultural regions of the world
[...] Read more.
Demographic growth, changes in diet, and reliance on first-generation biofuels are increasing the human demand for agricultural products, thereby enhancing the human pressure on global freshwater resources. Recent research on the food-water nexus has highlighted how some major agricultural regions of the world lack the water resources required to sustain current growth trends in crop production. To meet the increasing need for agricultural commodities with limited water resources, the water use efficiency of the agricultural sector must be improved. In this regard, recent work indicates that the often overlooked strategy of changing the crop distribution within presently cultivated areas offers promise. Here we investigate the extent to which water in the United States could be saved while improving yields simply by replacing the existing crops with more suitable ones. We propose crop replacement criteria that achieve this goal while preserving crop diversity, economic value, nitrogen fixation, and food protein production. We find that in the United States, these criteria would greatly improve calorie (+46%) and protein (+34%) production and economic value (+208%), with 5% water savings with respect to the present crop distribution. Interestingly, greater water savings could be achieved in water-stressed agricultural regions of the US such as California (56% water savings), and other western states. Full article
(This article belongs to the Special Issue Water Footprint Assessment)
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Open AccessArticle Channel Planform Dynamics Monitoring and Channel Stability Assessment in Two Sediment-Rich Rivers in Taiwan
Water 2017, 9(2), 84; doi:10.3390/w9020084
Received: 30 November 2016 / Accepted: 25 January 2017 / Published: 30 January 2017
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Abstract
Recurrent flood events induced by typhoons are powerful agents to modify channel morphology in Taiwan’s rivers. Frequent channel migrations reflect highly sensitive valley floors and increase the risk to infrastructure and residents along rivers. Therefore, monitoring channel planforms is essential for analyzing channel
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Recurrent flood events induced by typhoons are powerful agents to modify channel morphology in Taiwan’s rivers. Frequent channel migrations reflect highly sensitive valley floors and increase the risk to infrastructure and residents along rivers. Therefore, monitoring channel planforms is essential for analyzing channel stability as well as improving river management. This study analyzed annual channel changes along two sediment-rich rivers, the Zhuoshui River and the Gaoping River, from 2008 to 2015 based on satellite images of FORMOSAT-2. Channel areas were digitized from mid-catchment to river mouth (~90 km). Channel stability for reaches was assessed through analyzing the changes of river indices including braid index, active channel width, and channel activity. In general, the valley width plays a key role in braided degree, active channel width, and channel activity. These indices increase as the valley width expands whereas the braid index decreases slightly close to the river mouth due to the change of river types. This downstream pattern in the Zhuoshui River was interrupted by hydraulic construction which resulted in limited changes downstream from the weir, due to the lack of water and sediment supply. A 200-year flood, Typhoon Morakot in 2009, induced significant changes in the two rivers. The highly active landscape in Taiwan results in very sensitive channels compared to other regions. An integrated Sensitivity Index was proposed for identifying unstable reaches, which could be a useful reference for river authorities when making priorities in river regulation strategy. This study shows that satellite image monitoring coupled with river indices analysis could be an effective tool to evaluate spatial and temporal changes in channel stability in highly dynamic river systems. Full article
(This article belongs to the Special Issue Stream Channel Stability, Assessment, Modeling, and Mitigation)
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Open AccessArticle Removal of Pharmaceuticals from Wastewater by Intermittent Electrocoagulation
Water 2017, 9(2), 85; doi:10.3390/w9020085
Received: 17 October 2016 / Accepted: 24 January 2017 / Published: 31 January 2017
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Abstract
The continuous release of emerging contaminants (ECs) in the aquatic environment, as a result of the inadequate removal by conventional treatment methods, has prompted research to explore viable solutions to this rising global problem. One promising alternative is the use of electrochemical processes
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The continuous release of emerging contaminants (ECs) in the aquatic environment, as a result of the inadequate removal by conventional treatment methods, has prompted research to explore viable solutions to this rising global problem. One promising alternative is the use of electrochemical processes since they represent a simple and highly efficient technology with less footprint. In this paper, the feasibility of treating ECs (i.e., pharmaceuticals) using an intermittent electrocoagulation process, a known electrochemical technology, has been investigated. Diclofenac (DCF), carbamazepine (CBZ) and amoxicillin (AMX) were chosen as being representative of highly consumed drugs that are frequently detected in our water resources and were added in synthetic municipal wastewater. The removal efficiencies of both individual and combined pharmaceuticals were determined under different experimental conditions: hydraulic retention time (HRT) (6, 19 and 38 h), initial concentration (0.01, 4 and 10 mg/L) and intermittent application (5 min ON/20 min OFF) of current density (0.5, 1.15 and 1.8 mA/cm2). Results have shown that these parameters have significant effects on pharmaceutical degradation. Maximum removals (DCF = 90%, CBZ = 70% and AMX = 77%) were obtained at a current density of 0.5 mA/cm2, an initial concentration of 10 mg/L and HRT of 38 h. Full article
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Open AccessArticle Space–Time Characterization of Rainfall Field in Tuscany
Water 2017, 9(2), 86; doi:10.3390/w9020086
Received: 28 October 2016 / Accepted: 23 January 2017 / Published: 31 January 2017
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Abstract
Precipitation during the period 2001–2016 over the northern and central part of Tuscany was studied in order to characterize the rainfall regime. The dataset consisted of hourly cumulative rainfall series recorded by a network of 801 rain gauges. The territory was divided into
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Precipitation during the period 2001–2016 over the northern and central part of Tuscany was studied in order to characterize the rainfall regime. The dataset consisted of hourly cumulative rainfall series recorded by a network of 801 rain gauges. The territory was divided into 30 × 30 km2 square areas where the annual and seasonal Average Cumulative Rainfall (ACR) and its uncertainty were estimated using the Non-Parametric Ordinary Block Kriging (NPOBK) technique. The choice of area size was a compromise that allows a satisfactory spatial resolution and an acceptable uncertainty of ACR estimates. The daily ACR was estimated using a less computationally expensive technique, averaging the cumulative rainfall measurements in the area. The trend analysis of annual and seasonal ACR time series was performed by means of the Mann–Kendall test. Four climatic zones were identified: the north-western was the rainiest, followed by the north-eastern, northcentral and south-central. An overall increase in precipitation was identified, more intense in the north-west, and determined mostly by the increase in winter precipitation. On the entire territory, the number of rainy days, mean precipitation intensity and sum of daily ACR in four intensity groups were evaluated at annual and seasonal scale. The main result was a magnitude of the ACR trend evaluated as 35 mm/year, due mainly to an increase in light and extreme precipitations. This result is in contrast with the decreasing rainfall detected in the past decades. Full article
(This article belongs to the Special Issue Advances in Hydro-Meteorological Monitoring)
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Open AccessArticle Controlling the Formation of the Reaction Zone around an Injection Well during Subsurface Iron Removal
Water 2017, 9(2), 87; doi:10.3390/w9020087
Received: 30 November 2016 / Accepted: 26 January 2017 / Published: 31 January 2017
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Abstract
Tracer and pump tests including depth dependent water sampling were performed to investigate the flow conditions inside and in the vicinity of an injection well with two screen segments used for subsurface iron removal (SIR). A high resolution groundwater flow model of the
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Tracer and pump tests including depth dependent water sampling were performed to investigate the flow conditions inside and in the vicinity of an injection well with two screen segments used for subsurface iron removal (SIR). A high resolution groundwater flow model of the well and the adjacent aquifer with vertically varying dissolved iron concentration was calibrated and used to plan measures to manipulate the vertical outflow distribution of injected oxygen enriched water. The optimized injection regime was adopted in a pilot SIR test with the aim of increasing the treatment efficacy through a depth specific injection of water using an inflatable packer. When water was injected conventionally above the pump, the outward migration of the oxygen enriched water was non-uniform and disproportional to the iron concentration and resulted in an early iron breakthrough in the lower screen. The proportion of water injected into the lower iron-rich part of the aquifer increased as a packer was placed inside the well to seal 4/5 of the upper well screen length. Thereby, the efficiency coefficient increased by 50% and iron removal by 25%. The treatment efficiency at the site suffered from low alkalinity and pH-values below 5. Higher efficiency coefficients may have been achieved by the addition of alkalis prior to injection. Full article
(This article belongs to the Special Issue Water Quality Considerations for Managed Aquifer Recharge Systems)
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Open AccessArticle Quantity- and Quality-Based Farm Water Productivity in Wine Production: Case Studies in Germany
Water 2017, 9(2), 88; doi:10.3390/w9020088
Received: 29 November 2016 / Accepted: 24 January 2017 / Published: 1 February 2017
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Abstract
The German wine sector has encountered new challenges in water management recently. To manage water resources responsibly, it is necessary to understand the relationship between the input of water and the output of wine, in terms of quantity and quality. The objectives of
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The German wine sector has encountered new challenges in water management recently. To manage water resources responsibly, it is necessary to understand the relationship between the input of water and the output of wine, in terms of quantity and quality. The objectives of this study are to examine water use at the farm scale at three German wineries in Rhenish Hesse, and to develop and apply, for the first time, a quality-based indicator. Water use is analyzed in terms of wine production and wine-making over three years. After the spatial and temporal boundaries of the wineries and the water flows are defined, the farm water productivity indicator is calculated to assess water use at the winery scale. Farm water productivity is calculated using the AgroHyd Farmmodel modeling software. Average productivity on a quantity basis is 3.91 L wine per m3 of water. Productivity on a quality basis is 329.24 Oechsle per m3 of water. Water input from transpiration for wine production accounts for 99.4%–99.7% of total water input in the wineries, and, because irrigation is not used, precipitation is the sole source of transpired water. Future studies should use both quality-based and mass-based indicators of productivity. Full article
(This article belongs to the Special Issue Resilient Water Management in Agriculture)
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Open AccessArticle Water Use Efficiency Improvement against a Backdrop of Expanding City Agglomeration in Developing Countries—A Case Study on Industrial and Agricultural Water Use in the Bohai Bay Region of China
Water 2017, 9(2), 89; doi:10.3390/w9020089
Received: 26 September 2016 / Accepted: 23 January 2017 / Published: 2 February 2017
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Abstract
Most city agglomerations of developing countries face water shortages and pollution due to population growth and industrial aggregation. To meet such water security challenges, policy makers need to evaluate water use efficiency at the regional or basin level because the prosperity of city
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Most city agglomerations of developing countries face water shortages and pollution due to population growth and industrial aggregation. To meet such water security challenges, policy makers need to evaluate water use efficiency at the regional or basin level because the prosperity of city agglomerations is indispensable to the sustainable development of the region or basin. To solve the issue, this paper adopts a non-directional distance function within the framework of environmental production technology to measure water use efficiency. Based on the distance between actual water use efficiency and the ideal efficiency, it calculates the potential reduction space of water input and pollutants by slack adjustment. Added to the Malmquist index, it forms a non-radial Malmquist water use performance index, which can be divided into technological change and technical efficiency change, to measure dynamic water use efficiency. Further, water use efficiency change is analyzed from the perspectives of technological improvement and institutional construction. Bohai Bay city agglomeration, a typical water-deficient city agglomeration in China, is taken as a case study, and data on water resource, environment, and economy from 2011 to 2014 have been used. In conclusion, there is much space for water use efficiency improvement on the whole. However, even having considered potential reduction space of water input and pollutant discharge under current environmental production technology, it is still not enough to support the city agglomeration’s sustainable development. To relieve current potential water safety hazards, not only technical improvement but also institution innovation for highly efficient water use should be kept accelerating in Bohai Bay region. In terms of urban water management in developing countries, the research conclusion is of theoretical and practical significance. Full article
(This article belongs to the Special Issue Urban Water Challenges)
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Open AccessArticle Annual Changes in Seasonal River Water Temperatures in the Eastern and Western United States
Water 2017, 9(2), 90; doi:10.3390/w9020090
Received: 3 October 2016 / Revised: 19 January 2017 / Accepted: 2 February 2017 / Published: 4 February 2017
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Abstract
Changes in river water temperatures are anticipated to have direct effects on thermal habitat and fish population vital rates, and therefore, understanding temporal trends in water temperatures may be necessary for predicting changes in thermal habitat and how species might respond to such
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Changes in river water temperatures are anticipated to have direct effects on thermal habitat and fish population vital rates, and therefore, understanding temporal trends in water temperatures may be necessary for predicting changes in thermal habitat and how species might respond to such changes. However, many investigations into trends in water temperatures use regression methods that assume long-term monotonic changes in temperature, when in fact changes are likely to be nonmonotonic. Therefore, our objective was to highlight the need and provide an example of an analytical method to better quantify the short-term, nonmonotonic temporal changes in thermal habitat that are likely necessary to determine the effects of changing thermal conditions on fish populations and communities. To achieve this objective, this study uses Bayesian dynamic linear models (DLMs) to examine seasonal trends in river water temperatures from sites located in the eastern and western United States, regions that have dramatically different riverine habitats and fish communities. We estimated the annual rate of change in water temperature and found little evidence of seasonal changes in water temperatures in the eastern U.S. We found more evidence of warming for river sites located in the western U.S., particularly during the fall and winter seasons. Use of DLMs provided a more detailed view of temporal dynamics in river thermal habitat compared to more traditional methods by quantifying year-to-year changes and associated uncertainty, providing managers with the information needed to adapt decision making to short-term changes in habitat conditions that may be necessary for conserving aquatic resources in the face of a changing climate. Full article
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Open AccessArticle Soil Moisture Variation in a Farmed Dry-Hot Valley Catchment Evaluated by a Redundancy Analysis Approach
Water 2017, 9(2), 92; doi:10.3390/w9020092
Received: 24 October 2016 / Revised: 6 January 2017 / Accepted: 3 February 2017 / Published: 7 February 2017
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Abstract
Farmed catchments have greater temporal and spatial heterogeneity of soil moisture than natural catchments. Increased knowledge about the variation of soil moisture in farmed catchments has important implications for the adoption of appropriate tillage measures for agriculture. The purpose of this study was
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Farmed catchments have greater temporal and spatial heterogeneity of soil moisture than natural catchments. Increased knowledge about the variation of soil moisture in farmed catchments has important implications for the adoption of appropriate tillage measures for agriculture. The purpose of this study was to determine the spatial and temporal variability of soil moisture as controlled by the environment on a farmed catchment in a typical dry-hot valley (DHV) by integrating geostatistical and redundancy analysis (RDA). We monitored soil moisture in topsoil (0–20 cm) and subsoil (20–40 cm) layers at 51 points on eight occasions from July 2012 to March 2014, and determined the environmental factors of soil particle-size distribution, soil organic matter, slope aspect, slope gradient, elevation, and a topographic wetness index (WI) modified for semiarid conditions at each point. The results showed that, under the influence of high evaporation, soil moisture in the topsoil was significantly lower than that of subsoil in the DHV. In this study, we observed a strong temporal variation of soil moisture, which was influenced by the seasonal variation of crop cover and lagged behind that of rainfall. Relatively high soil moisture levels were found on the watershed divide and hillside sites of the catchment, and lower on the valleyside sites. Different from other studies, RDA analysis indicated that the WI was not correlated with soil moisture in the DHV; instead, clay and sand levels were the dominant control factor of soil moisture in the farmed DHV. We proposed that soil erosion in the DHV could lead to such increases of sand and decreases of clay content, thus influencing soil moisture content. Soil and water conservation measures will be especially important for valleyside sites with steep slopes. Full article
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Open AccessArticle Variability in the Water Footprint of Arable Crop Production across European Regions
Water 2017, 9(2), 93; doi:10.3390/w9020093
Received: 24 October 2016 / Revised: 11 December 2016 / Accepted: 31 January 2017 / Published: 8 February 2017
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Abstract
Crop growth and yield are affected by water use during the season: the green water footprint (WF) accounts for rain water, the blue WF for irrigation and the grey WF for diluting agri-chemicals. We calibrated crop yield for FAO’s water balance model “Aquacrop”
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Crop growth and yield are affected by water use during the season: the green water footprint (WF) accounts for rain water, the blue WF for irrigation and the grey WF for diluting agri-chemicals. We calibrated crop yield for FAO’s water balance model “Aquacrop” at field level. We collected weather, soil and crop inputs for 45 locations for the period 1992–2012. Calibrated model runs were conducted for wheat, barley, grain maize, oilseed rape, potato and sugar beet. The WF of cereals could be up to 20 times larger than the WF of tuber and root crops; the largest share was attributed to the green WF. The green and blue WF compared favourably with global benchmark values (R2 = 0.64–0.80; d = 0.91–0.95). The variability in the WF of arable crops across different regions in Europe is mainly due to variability in crop yield ( c v ¯ = 45%) and to a lesser extent to variability in crop water use ( c v ¯ = 21%). The WF variability between countries ( c v ¯ = 14%) is lower than the variability between seasons ( c v ¯ = 22%) and between crops ( c v ¯ = 46%). Though modelled yields increased up to 50% under sprinkler irrigation, the water footprint still increased between 1% and 25%. Confronted with drainage and runoff, the grey WF tended to overestimate the contribution of nitrogen to the surface and groundwater. The results showed that the water footprint provides a measurable indicator that may support European water governance. Full article
(This article belongs to the Special Issue Water Footprint Assessment)
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Open AccessArticle Small Scale Direct Potable Reuse (DPR) Project for a Remote Area
Water 2017, 9(2), 94; doi:10.3390/w9020094
Received: 8 December 2016 / Revised: 25 January 2017 / Accepted: 4 February 2017 / Published: 8 February 2017
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Abstract
An Advanced Water Treatment Plant (AWTP) for potable water recycling in Davis Station Antarctica was trialed using secondary effluent at Selfs Point in Hobart, Tasmania, for nine months. The trials demonstrated the reliability of performance of a seven barrier treatment process consisting of
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An Advanced Water Treatment Plant (AWTP) for potable water recycling in Davis Station Antarctica was trialed using secondary effluent at Selfs Point in Hobart, Tasmania, for nine months. The trials demonstrated the reliability of performance of a seven barrier treatment process consisting of ozonation, ceramic microfiltration (MF), biologically activated carbon, reverse osmosis, ultra-violet disinfection, calcite contactor and chlorination. The seven treatment barriers were required to meet the high log removal values (LRV) required for pathogens in small systems during disease outbreak, and on-line verification of process performance was required for operation with infrequent operator attention. On-line verification of pathogen LRVs, a low turbidity filtrate of approximately 0.1 NTU (Nephelometric Turbidity Unit), no long-term fouling and no requirement for clean-in-place (CIP) was achieved with the ceramic MF. A pressure decay test was also reliably implemented on the reverse osmosis system to achieve a 2 LRV for protozoa, and this barrier required only 2–3 CIP treatments each year. The ozonation process achieved 2 LRV for bacteria and virus with no requirement for an ozone residual, provided the ozone dose was >11.7 mg/L. Extensive screening using multi-residue gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry (LC–MS) database methods that can screen for more than 1200 chemicals found that few chemicals pass through the barriers to the final product and rejected (discharge) water streams. The AWTP plant required 1.93 kWh/m3 when operated in the mode required for Davis Station and was predicted to require 1.27 kWh/m3 if scaled up to 10 ML/day. The AWTP will be shipped to Davis Station for further trials before possible implementation for water recycling. The process may have application in other small remote communities. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle Borehole Logging and Slug Tests for Evaluating the Applicability of Electrical Resistivity Tomography for Groundwater Exploration in Nampula Complex, Mozambique
Water 2017, 9(2), 95; doi:10.3390/w9020095
Received: 8 December 2016 / Revised: 21 January 2017 / Accepted: 3 February 2017 / Published: 8 February 2017
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Abstract
In Nampula province, Mozambique, there is a high number of water wells considered as having failed for having too low a pumping yield. Two Electrical Resistivity Tomography (ERT) measurement campaigns were conducted in the area for evaluating the reasons of failures. However, in
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In Nampula province, Mozambique, there is a high number of water wells considered as having failed for having too low a pumping yield. Two Electrical Resistivity Tomography (ERT) measurement campaigns were conducted in the area for evaluating the reasons of failures. However, in some cases it was difficult to verify and interpret the ERT results by only using the inadequate lithological description presented in drilling reports. In this paper the integration of borehole logging and slug testing is presented as a solution to add more information and to enhance the interpretation of ERT models. The borehole logging tool measured resistivity, magnetic susceptibility and natural gamma. The logging results proved that the ERT models are accurate in estimating the resistivity for basement (>1400 Ωm), fractured layer (220–1400 Ωm), semi-weathered layer with clay accumulation (10–220 Ωm), and weathered and leached layer (220–2700 Ωm). The slug testing gave results of high hydraulic conductivity (K) values where the ERT indicates well-developed weathered and fractured layers, and low K values where these are less developed. The borehole interpretation can be extrapolated using the ERT model to give a geometric characterization of the aquifer. Therefore, the implementation of the ERT method in groundwater exploration is encouraged. Full article
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Open AccessArticle Evaluation of Peak Water Demand Factors in Puglia (Southern Italy)
Water 2017, 9(2), 96; doi:10.3390/w9020096
Received: 30 November 2016 / Revised: 23 January 2017 / Accepted: 6 February 2017 / Published: 8 February 2017
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Abstract
In the design of a water supply network, the use of traditional formulas of the peak factor may lead to over-dimensioning the network pipelines, especially in small towns. This discrepancy is probably due to changes in human habits as a consequence of a
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In the design of a water supply network, the use of traditional formulas of the peak factor may lead to over-dimensioning the network pipelines, especially in small towns. This discrepancy is probably due to changes in human habits as a consequence of a general improvement of living conditions. Starting from these considerations, and given the availability of a wide random sample data, an analysis of the water demand for several towns in Puglia was carried out, leading to the definition of a relationship between the above mentioned peak factor and the number of inhabitants, based on a stochastic approach. An interesting outcome of this study is that the design of water supply network is possible without considering the use of monthly and weekly peak factors, since the current water demands appear not specifically sensitive to these variations; moreover, the magnitude of the peak factor, as shown by measured data, is considerably lower compared to literature values, especially for small towns. Full article
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Open AccessArticle Energy Recovery in Existing Water Networks: Towards Greater Sustainability
Water 2017, 9(2), 97; doi:10.3390/w9020097
Received: 24 October 2016 / Revised: 24 January 2017 / Accepted: 3 February 2017 / Published: 8 February 2017
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Abstract
Analyses of possible synergies between energy recovery and water management are essential for achieving sustainable improvements in the performance of irrigation water networks. Improving the energy efficiency of water systems by hydraulic energy recovery is becoming an inevitable trend for energy conservation, emissions
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Analyses of possible synergies between energy recovery and water management are essential for achieving sustainable improvements in the performance of irrigation water networks. Improving the energy efficiency of water systems by hydraulic energy recovery is becoming an inevitable trend for energy conservation, emissions reduction, and the increase of profit margins as well as for environmental requirements. This paper presents the state of the art of hydraulic energy generation in drinking and irrigation water networks through an extensive review and by analyzing the types of machinery installed, economic and environmental implications of large and small hydropower systems, and how hydropower can be applied in water distribution networks (drinking and irrigation) where energy recovery is not the main objective. Several proposed solutions of energy recovery by using hydraulic machines increase the added value of irrigation water networks, which is an open field that needs to be explored in the near future. Full article
(This article belongs to the Special Issue Water Systems towards New Future Challenges)
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Open AccessArticle Experimental and Numerical Analysis of a Water Emptying Pipeline Using Different Air Valves
Water 2017, 9(2), 98; doi:10.3390/w9020098
Received: 5 December 2016 / Revised: 25 January 2017 / Accepted: 3 February 2017 / Published: 8 February 2017
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Abstract
The emptying procedure is a common operation that engineers have to face in pipelines. This generates subatmospheric pressure caused by the expansion of air pockets, which can produce the collapse of the system depending on the conditions of the installation. To avoid this
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The emptying procedure is a common operation that engineers have to face in pipelines. This generates subatmospheric pressure caused by the expansion of air pockets, which can produce the collapse of the system depending on the conditions of the installation. To avoid this problem, engineers have to install air valves in pipelines. However, if air valves are not adequately designed, then the risk in pipelines continues. In this research, a mathematical model is developed to simulate an emptying process in pipelines that can be used for planning this type of operation. The one-dimensional proposed model analyzes the water phase propagation by a new rigid model and the air pockets effect using thermodynamic formulations. The proposed model is validated through measurements of the air pocket absolute pressure, the water velocity and the length of the emptying columns in an experimental facility. Results show that the proposed model can accurately predict the hydraulic characteristic variables. Full article
(This article belongs to the Special Issue Water Systems towards New Future Challenges)
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Open AccessArticle Collaborative Modeling to Assess Drought Resiliency of Snow‐Fed River Dependent Communities in the Western United States: A Case Study in the Truckee‐Carson River System
Water 2017, 9(2), 99; doi:10.3390/w9020099
Received: 20 October 2016 / Accepted: 3 February 2017 / Published: 9 February 2017
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Abstract
Assessing the drought resilience of snow‐fed river dependent communities in the arid Western United States has taken on critical importance in response to changing climatic conditions. The process of assessing drought resiliency involves understanding the extent to which snow‐fed dependent communities can absorb
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Assessing the drought resilience of snow‐fed river dependent communities in the arid Western United States has taken on critical importance in response to changing climatic conditions. The process of assessing drought resiliency involves understanding the extent to which snow‐fed dependent communities can absorb the effects of uncertain and variable water supplies while acknowledging and encouraging their capacity for adaptation. Participatory research approaches are particularly well suited to assess resiliency in this context because they rely upon local water managers’ knowledge and perspectives. The research presented here provides measured insight into local water managers’ perceptions of drought resiliency in the Truckee‐Carson River System in northwestern Nevada. These findings are reported in the context of the collaborative modeling research design developed for this case study. The objectives of this study are: (1) to define resiliency and present a rationale for a participatory approach to assess drought resiliency in snow‐fed arid river basins in the Western United States; (2) to outline collaborative modeling as a participatory research design developed for the Truckee‐Carson River System case study area; (3) to describe the development and implementation of a resiliency assessment undertaken to implement this research design; (4) to highlight selected results of the assessment, summarizing interviews with 66 water managers in the case study area; (5) to discuss the use of assessment findings to inform collaborative modeling toward adaptation strategies; and (6) to review lessons learned to date from the collaborative modeling case study and note opportunities for further exploration. According to water managers surveyed, climate change is very important and is mobilizing adaptation strategies that include improvements in communication and coordination with other water managers, monitoring and data collection,and planning. The majority of water managers indicate that future adaptation requires modifying institutionalized water management regimes to allow for temporary water leasing programs, water right stacking on the most productive agricultural lands while fallowing marginal lands,incentivizing water conservation, reducing or eliminating residential landscaping, and recruiting less water intensive industry to the region. Full article
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Open AccessArticle Modeling Glacier Mass Balance and Runoff in the Koxkar River Basin on the South Slope of the Tianshan Mountains, China, from 1959 to 2009
Water 2017, 9(2), 100; doi:10.3390/w9020100
Received: 28 October 2016 / Revised: 18 January 2017 / Accepted: 22 January 2017 / Published: 8 February 2017
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Abstract
Water resources provided by alpine glaciers are an important pillar for people in the arid regions of west China. In this study, the Hydrologiska Byrans Vattenavdelning (HBV) light model was applied to simulate glacier mass balance (GMB) and runoff in the Koxkar River
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Water resources provided by alpine glaciers are an important pillar for people in the arid regions of west China. In this study, the Hydrologiska Byrans Vattenavdelning (HBV) light model was applied to simulate glacier mass balance (GMB) and runoff in the Koxkar River Basin (KRB) on the south slope of Mount Tumur, in the western Tianshan Mountains. Daily temperature and precipitation were calculated by multiple linear regressions and gradient-inverse distance weighting, respectively, based on in-situ observed data by automatic weather stations (AWSs) in the Koxkar River Basin (KRB; 2007–2009) and four meteorological stations neighboring the basin (1959–2009). Observed daily air temperature and precipitation were input into HBV model. The runoff data in 2007/2008 and 2008/2009 were used to calibrate and validate the model in 2009/2010 and 2010/2011. Generally, the model simulated runoff very well. The annual glacier mass balance and runoff were calculated by the HBV model and were driven by interpolated meteorological data between 1959 and 2009. The calculated glacier mass balances were reasonable, and were compared with nearby glaciers. The results indicate the decreasing trend of mass balance in the Koxkar Glacier, with an average value of ablation of −370.4 mm·a−1 between 1959 and 2009. The annual runoff showed an increasing trend (5.51 mm·a−1). Further analysis showed that the runoff is more sensitive to temperature than precipitation in KRB. Full article
(This article belongs to the Special Issue Global Warming Impacts on Mountain Glaciers and Communities)
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Open AccessArticle Applying SHETRAN in a Tropical West African Catchment (Dano, Burkina Faso)—Calibration, Validation, Uncertainty Assessment
Water 2017, 9(2), 101; doi:10.3390/w9020101
Received: 2 December 2016 / Accepted: 4 February 2017 / Published: 9 February 2017
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Abstract
This study presents the calibration and validation of the physically based spatially distributed hydrological and soil erosion model SHETRAN for the Dano catchment, Burkina Faso. A sensitivity analysis of six model parameters was performed to assess the model response and to reduce the
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This study presents the calibration and validation of the physically based spatially distributed hydrological and soil erosion model SHETRAN for the Dano catchment, Burkina Faso. A sensitivity analysis of six model parameters was performed to assess the model response and to reduce the number of parameters for calibration. The hydrological component was calibrated and validated using observed discharge data of two years. Statistical quality measures (R2, NSE, KGE) ranged from 0.79 to 0.66 during calibration and validation. The calibrated hydrological component was used to feed the erosion modeling. The simulated suspended sediment load (SSL) was compared with turbidity‐based measurements of SSL of two years. Achieved quality measures are comparable to other SHETRAN studies. Uncertainties of measured discharge and suspended sediment concentration were determined to assess the propagated uncertainty of SSL. The comparison of measurement uncertainties of discharge and SSL with parameter uncertainty of the corresponding model output showed that simulated discharge and SSL were frequently outside the large measured uncertainty bands. A modified NSE was used to incorporate measurement and parameter uncertainty into the efficiency evaluation of the model. The analyses of simulated erosion sources and spatial patterns showed the importance of river erosion contributing more than 60% to the total simulated sediment loss. Full article
(This article belongs to the Special Issue Soil Erosion by Water)
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Open AccessArticle Surface Water and Groundwater Interactions in Traditionally Irrigated Fields in Northern New Mexico, U.S.A.
Water 2017, 9(2), 102; doi:10.3390/w9020102
Received: 18 December 2016 / Revised: 24 January 2017 / Accepted: 3 February 2017 / Published: 10 February 2017
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Abstract
Better understanding of surface water (SW) and groundwater (GW) interactions and water balances has become indispensable for water management decisions. This study sought to characterize SW-GW interactions in three crop fields located in three different irrigated valleys in northern New Mexico by (1)
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Better understanding of surface water (SW) and groundwater (GW) interactions and water balances has become indispensable for water management decisions. This study sought to characterize SW-GW interactions in three crop fields located in three different irrigated valleys in northern New Mexico by (1) estimating deep percolation (DP) below the root zone in flood-irrigated crop fields; and (2) characterizing shallow aquifer response to inputs from DP associated with irrigation. Detailed measurements of irrigation water application, soil water content fluctuations, crop field runoff, and weather data were used in the water budget calculations for each field. Shallow wells were used to monitor groundwater level response to DP inputs. The amount of DP was positively and significantly related to the total amount of irrigation water applied for the Rio Hondo and Alcalde sites, but not for the El Rito site. The average irrigation event DP using data for the complete irrigation season at each of the three sites was 77.0 mm at El Rito, 54.5 mm at Alcalde and 53.1 mm at Rio Hondo. Groundwater level rise compared to pre-irrigation event water levels ranged from 3 to 1870 mm, and was influenced by differences in irrigation practices between sites. Crop evapotranspiration estimates averaged across irrigation events were highest in Rio Hondo (22.9 mm), followed by El Rito (14.4 mm) and Alcalde (10.4 mm). Results from this study indicate there are strong surface water-groundwater connections in traditionally irrigated systems of northern New Mexico, connections that may be employed to better manage groundwater recharge and river flow. Full article
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Open AccessArticle Assessing the Impact of Climate Change and Extreme Value Uncertainty to Extreme Flows across Great Britain
Water 2017, 9(2), 103; doi:10.3390/w9020103
Received: 23 December 2016 / Accepted: 3 February 2017 / Published: 9 February 2017
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Abstract
Floods are the most common and widely distributed natural risk, causing over £1 billion of damage per year in the UK as a result of recent events. Climatic projections predict an increase in flood risk; it becomes urgent to assess climate change impact
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Floods are the most common and widely distributed natural risk, causing over £1 billion of damage per year in the UK as a result of recent events. Climatic projections predict an increase in flood risk; it becomes urgent to assess climate change impact on extreme flows, and evaluate uncertainties related to these projections. This paper aims to assess the changes in extreme runoff for the 1:100 year return period across Great Britain as a result of climate change using the Future Flows Hydrology database. The Generalised Extreme Value (GEV) and Generalised Pareto (GP) models are automatically fitted for 11‐member ensemble flow series available for the baseline and the 2080s. The analysis evaluates the uncertainty related to the Extreme Value (EV) and climate model parameters. Results suggest that GP and GEV give similar runoff estimates and uncertainties. From the baseline to the 2080s, increasing estimate and uncertainties is evident in east England. With the GEV the uncertainty attributed to the climate model parameters is greater than for the GP (around 60% and 40% of the total uncertainty, respectively). This shows that when fitting both EV models, the uncertainty related to their parameters has to be accounted for to assess extreme runoffs. Full article
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Open AccessArticle A Percolation‐Based Approach to Scaling Infiltration and Evapotranspiration
Water 2017, 9(2), 104; doi:10.3390/w9020104
Received: 9 November 2016 / Accepted: 6 February 2017 / Published: 9 February 2017
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Abstract
Optimal flow paths obtained from percolation theory provide a powerful tool that can be used to characterize properties associated with flow such as soil hydraulic conductivity, as well as other properties influenced by flow connectivity and topology. A recently proposed scaling theory for
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Optimal flow paths obtained from percolation theory provide a powerful tool that can be used to characterize properties associated with flow such as soil hydraulic conductivity, as well as other properties influenced by flow connectivity and topology. A recently proposed scaling theory for vegetation growth appeals to the tortuosity of optimal paths from percolation theory to define the spatio‐temporal scaling of the root radial extent (or, equivalently, plant height). Root radial extent measures the maximum horizontal distance between a plant shoot and the root tips. We apply here the same scaling relationship to unsteady (horizontal) flow associated with plant transpiration. The pore‐scale travel time is generated from the maximum flow rate under saturated conditions and a typical pore size. At the field‐scale, the characteristic time is interpreted as the growing season duration, and the characteristic length is derived from the measured evapotranspiration in that period. We show that the two scaling results are equivalent, and they are each in accord with observed vegetation growth limits, as well as with actual limiting transpiration values. While the conceptual approach addresses transpiration, most accessed data are for evapotranspiration. The equivalence of the two scaling approaches suggests that, if horizontal flow is the dominant pathway in plant transpiration, horizontal unsteady flow follows the same scaling relationship as root growth. Then, we propose a corresponding scaling relationship to vertical infiltration, a hypothesis which is amenable to testing using infiltration results of Sharma and co‐authors. This alternate treatment of unsteady vertical flow may be an effective alternative to the commonly applied method based on the diffusion of water over a continuum as governed by Richards’ equation. Full article
(This article belongs to the Special Issue Water and Solute Transport in Vadose Zone)
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Open AccessArticle Machine Learning Algorithms for the Forecasting of Wastewater Quality Indicators
Water 2017, 9(2), 105; doi:10.3390/w9020105
Received: 21 November 2016 / Accepted: 6 February 2017 / Published: 9 February 2017
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Abstract
Stormwater runoff is often contaminated by human activities. Stormwater discharge into water bodies significantly contributes to environmental pollution. The choice of suitable treatment technologies is dependent on the pollutant concentrations. Wastewater quality indicators such as biochemical oxygen demand (BOD5), chemical oxygen demand (COD),
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Stormwater runoff is often contaminated by human activities. Stormwater discharge into water bodies significantly contributes to environmental pollution. The choice of suitable treatment technologies is dependent on the pollutant concentrations. Wastewater quality indicators such as biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), and total dissolved solids (TDS) give a measure of the main pollutants. The aim of this study is to provide an indirect methodology for the estimation of the main wastewater quality indicators, based on some characteristics of the drainage basin. The catchment is seen as a black box: the physical processes of accumulation, washing, and transport of pollutants are not mathematically described. Two models deriving from studies on artificial intelligence have been used in this research: Support Vector Regression (SVR) and Regression Trees (RT). Both the models showed robustness, reliability, and high generalization capability. However, with reference to coefficient of determination R2 and root‐mean square error, Support Vector Regression showed a better performance than Regression Tree in predicting TSS, TDS, and COD. As regards BOD5, the two models showed a comparable performance. Therefore, the considered machine learning algorithms may be useful for providing an estimation of the values to be considered for the sizing of the treatment units in absence of direct measures. Full article
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Open AccessArticle Flow Patterns and Morphological Changes in a Sandy Meander Bend during a Flood—Spatially and Temporally Intensive ADCP Measurement Approach
Water 2017, 9(2), 106; doi:10.3390/w9020106
Received: 25 November 2016 / Revised: 27 January 2017 / Accepted: 4 February 2017 / Published: 10 February 2017
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Abstract
The fluvio-geomorphological processes in meander bends are spatially uneven in distribution. Typically, higher velocities and erosion take place near the outer bank beyond the bend apex, while the inner bend point bar grows laterally towards the outer bank, increasing the bend amplitude. These
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The fluvio-geomorphological processes in meander bends are spatially uneven in distribution. Typically, higher velocities and erosion take place near the outer bank beyond the bend apex, while the inner bend point bar grows laterally towards the outer bank, increasing the bend amplitude. These dynamics maintain the meander evolution. Even though this development is found in meandering rivers independent of soil or environmental characteristics, each river still seems to behave unpredictably. The special mechanisms that determine the rate and occasion of morphological changes remain unclear. The aim of this study is to offer new insights regarding flow-induced morphological changes in meander using a novel study approach. We focused on short-term and small-spatial-scale changes by conducting a spatially and temporally (daily) intensive survey during a flood (a period of nine days) with an ADCP attached to a remotely controlled mini-boat. Based on our analysis, the flood duration and the rate of discharge increase and decrease seems to play key roles in determining channel changes by controlling the flow velocities and depth and the backwater effect may have notable influence on the morphological processes. We discuss themes such as the interaction of inner and outer bend processes and the longer-term development of meander bends. Full article
(This article belongs to the Special Issue Stream Channel Stability, Assessment, Modeling, and Mitigation)
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Open AccessArticle Accomplishing Water Strategy Policies in Hospitals: The Role of Management Information Systems and Managerial Styles
Water 2017, 9(2), 107; doi:10.3390/w9020107
Received: 31 October 2016 / Revised: 1 February 2017 / Accepted: 7 February 2017 / Published: 10 February 2017
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Abstract
Hospitals are using more sophisticated and comprehensive management information systems to implement multiple strategic policies towards water cost saving and water quality enhancement. However, they do not always achieve the intended strategic goals. This paper analyzes how managerial styles interact with sophisticated management
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Hospitals are using more sophisticated and comprehensive management information systems to implement multiple strategic policies towards water cost saving and water quality enhancement. However, they do not always achieve the intended strategic goals. This paper analyzes how managerial styles interact with sophisticated management information systems to achieve different water strategic priorities. How proactive vs. reactive managerial styles moderate the effects of management information systems on water cost saving and water quality enhancement is analyzed. Relationships are explored using data collected from 122 general services directors in Spanish public hospitals. The findings show a positive effect of sophisticated management information systems on the achievement of water policies focused on cost saving and quality enhancement. Results also show a different moderated effect of managerial styles; thus, sophisticated management information systems with a proactive managerial style facilitate managers to achieve better water quality policies rather than water cost saving policies. Full article
(This article belongs to the collection Water Policy Collection)
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Open AccessArticle Potential of Rhodobacter capsulatus Grown in Anaerobic-Light or Aerobic-Dark Conditions as Bioremediation Agent for Biological Wastewater Treatments
Water 2017, 9(2), 108; doi:10.3390/w9020108
Received: 4 October 2016 / Revised: 23 January 2017 / Accepted: 2 February 2017 / Published: 10 February 2017
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Abstract
The use of microorganisms to clean up wastewater provides a cheaper alternative to the conventional treatment plant. The efficiency of this method can be improved by the choice of microorganism with the potential of removing contaminants. One such group is photosynthetic bacteria. Rhodobacter
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The use of microorganisms to clean up wastewater provides a cheaper alternative to the conventional treatment plant. The efficiency of this method can be improved by the choice of microorganism with the potential of removing contaminants. One such group is photosynthetic bacteria. Rhodobacter capsulatus is a purple non-sulfur bacterium (PNSB) found to be capable of different metabolic activities depending on the environmental conditions. Cell growth in different media and conditions was tested, obtaining a concentration of about 108 CFU/mL under aerobic-dark and 109 CFU/mL under anaerobic-light conditions. The biomass was then used as a bioremediation agent for denitrification and nitrification of municipal wastewater to evaluate the potential to be employed as an additive in biological wastewater treatment. Inoculating a sample of mixed liquor withdrawn from the municipal wastewater treatment plant with R. capsulatus grown in aerobic-dark and anaerobic-light conditions caused a significant decrease of N-NO3 (>95%), N-NH3 (70%) and SCOD (soluble chemical oxygen demand) (>69%), independent of the growth conditions. A preliminary evaluation of costs indicated that R. capsulatus grown in aerobic-dark conditions could be more convenient for industrial application. Full article
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Open AccessArticle Contemporary and Future Characteristics of Precipitation Indices in the Kentucky River Basin
Water 2017, 9(2), 109; doi:10.3390/w9020109
Received: 31 August 2016 / Accepted: 8 February 2017 / Published: 10 February 2017
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Abstract
Climatic variability can lead to large‐scale alterations in the hydrologic cycle, some of which can be characterized in terms of indices involving precipitation depth, duration and frequency. This study evaluated the spatiotemporal behavior of precipitation indices over the Kentucky River watershed for both
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Climatic variability can lead to large‐scale alterations in the hydrologic cycle, some of which can be characterized in terms of indices involving precipitation depth, duration and frequency. This study evaluated the spatiotemporal behavior of precipitation indices over the Kentucky River watershed for both the baseline period of 1986–2015 and late‐century time frame of 2070–2099. Historical precipitation data were collected from 16 weather stations in the watershed, while future rainfall time‐series were obtained from an ensemble of 10 Coupled Model Intercomparison Project Phase 5 (CMIP5) global circulation models under two future emission pathways: Representative Concentration Pathways (RCP) 4.5 and 8.5. Annual trends in seven precipitation indices were analyzed: total precipitation on wet days (PRCPTOT), maximum length (in days) of dry and wet periods (CDD and CWD, respectively), number of days with precipitation depth ≥20 mm (R20mm), maximum five‐day precipitation depth (RX5day), simple daily precipitation index (SDII) and standardized precipitation index (SPI, a measure of drought severity). Non‐parametric Mann–Kendall test results indicated significant trends for only ≈11% of the stationindex combinations, corresponding to generally increasing trends in PRCPTOT, CWD, R20mm and RX5day and negative trends for the others. Projected magnitudes for PRCPTOT, CDD, CWD, RX5day and SPI, indices associated with the macroweather regime, demonstrated general consistency with trends previously identified and indicated modest increases in PRCPTOT and CWD, slight decrease in CDD, mixed results for RX5day, and increased non‐drought years in the late century relative to the baseline period. Late‐century projections for the remaining indices (SDII, R20mm) demonstrated behavior counter to trends in the trends identified in the baseline period data, suggesting that these indices—which are more closely linked with the weather regime and daily GCM outputs—were relatively less robust. Full article
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Open AccessArticle Effects of Different In-Stream Structure Representations in Computational Fluid Dynamics Models—Taking Engineered Log Jams (ELJ) as an Example
Water 2017, 9(2), 110; doi:10.3390/w9020110
Received: 15 November 2016 / Accepted: 3 February 2017 / Published: 10 February 2017
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Abstract
In-streamstructurescontributegreatlytothebiodiversityinstreamsandplayanimportant role in restoring and protecting rivers. They usually have complex geometries. To evaluate their impact and effectiveness, computational models are increasingly used. However, how to faithfully represent them in computer models remains a challenge. Often, simplifications have to be made. This work
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In-streamstructurescontributegreatlytothebiodiversityinstreamsandplayanimportant role in restoring and protecting rivers. They usually have complex geometries. To evaluate their impact and effectiveness, computational models are increasingly used. However, how to faithfully represent them in computer models remains a challenge. Often, simplifications have to be made. This work evaluated the effects of geometric simplification of an example in-stream structure, an engineered log jam (ELJ), in computational models. Three different representations were considered, namely full resolution, the porous media model and the solid barrier model. The turbulent flow was resolved with large eddy simulation (LES). First, the simulations were validated with a physical experiment in a flume. Then, the results from the three models were comparedandanalyzedonvariousaspectsrelatedtothestabilityandfunctionalitiesofthestructures. Unsurprisingly, it is found that the porous media model and the solid barrier model, which are computationally economic, can describe the flow dynamics only to some extent. From the calibration ofdragforceandwakelength,wefoundthattheequivalentgrainsized50 intheporositymodelshould scale as the key element diameter for the simulated ELJ. A wake length scale analysis was performed for the semi-bounded flow around this in-stream structure near the bank. The length estimator in the literature for unbounded vegetation patches can be used with modifications. The results also show that the flow passing through the porous in-stream structure has a significant impact on mean velocity, turbulence kinetic energy, sediment transport capacity and integral wake length. Since geometrically-fully-resolved simulations are not currently feasible for engineering practices, the following suggestions are made based on this study. If the near-field and wake are important for the purpose of the structure, the well-calibrated porosity model seems to perform better than the solid barrier model. However, care needs to be taken when interpreting the results because this work also identified substantial loss of physical information with the porosity model. When the emphasis is the far field away from the structure, both the porosity model and the solid barrier model give comparable results Full article
(This article belongs to the Special Issue Stream Channel Stability, Assessment, Modeling, and Mitigation)
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Open AccessArticle Hydrological Modeling of Highly Glacierized Basins (Andes, Alps, and Central Asia)
Water 2017, 9(2), 111; doi:10.3390/w9020111
Received: 4 December 2016 / Revised: 26 January 2017 / Accepted: 3 February 2017 / Published: 10 February 2017
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Abstract
The Soil and Water Assessment Tool (SWAT) was used to simulate five glacierized river basins that are global in coverage and vary in climate. The river basins included the Narayani (Nepal), Vakhsh (Central Asia), Rhone (Switzerland), Mendoza (Central Andes, Argentina), and Central Dry
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The Soil and Water Assessment Tool (SWAT) was used to simulate five glacierized river basins that are global in coverage and vary in climate. The river basins included the Narayani (Nepal), Vakhsh (Central Asia), Rhone (Switzerland), Mendoza (Central Andes, Argentina), and Central Dry Andes (Chile), with a total area of 85,000 km2. A modified SWAT snow algorithm was applied in order to consider spatial variation of associated snowmelt/accumulation by elevation band across each subbasin. In previous studies, melt rates varied as a function of elevation because of an air temperature gradient while the snow parameters were constant throughout the entire basin. A major improvement of the new snow algorithm is the separation of the glaciers from seasonal snow based on their characteristics. Two SWAT snow algorithms were evaluated in simulation of monthly runoff from the glaciered watersheds: (1) the snow parameters are lumped (constant throughout the entire basin) and (2) the snow parameters are spatially variable based on elevation bands of a subbasin (modified snow algorithm). Applying the distributed SWAT snow algorithm improved the model performance in simulation of monthly runoff with snow-glacial regime, so that mean RSR decreased to 0.49 from 0.55 and NSE increased to 0.75 from 0.69. Improvement of model performance was negligible in simulations of monthly runoff from the basins with a monsoon runoff regime. Full article
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Open AccessArticle Performance of Denitrifying Bioreactors at Reducing Agricultural Nitrogen Pollution in a Humid Subtropical Coastal Plain Climate
Water 2017, 9(2), 112; doi:10.3390/w9020112
Received: 21 December 2016 / Accepted: 6 February 2017 / Published: 10 February 2017
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Abstract
Denitrifying bioreactors are an agricultural best management practice developed in the midwestern United States to treat agricultural drainage water enriched with nitrate‐nitrogen (NO3N). The practice is spreading rapidly to agricultural regions with poor water quality due to nutrient enrichment. This makes it imperative
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Denitrifying bioreactors are an agricultural best management practice developed in the midwestern United States to treat agricultural drainage water enriched with nitrate‐nitrogen (NO3N). The practice is spreading rapidly to agricultural regions with poor water quality due to nutrient enrichment. This makes it imperative to track bioreactor NO3‐N reduction efficiency as this practice gets deployed to new regions. This study evaluated the application and performance of denitrifying bioreactors in the humid subtropical coastal plain environment of the Chesapeake Bay catchment to provide data about regionally specific NO3‐N reduction efficiencies. NO3‐N samples were taken before and after treatment at three denitrifying bioreactors, in addition to other nutrients (orthophosphate‐phosphorus, PO4‐P; ammonium‐nitrogen, NH4‐N; total nitrogen, TN; total phosphorus, TP) and water quality parameters (dissolved oxygen, DO; oxidation reduction potential, ORP; pH; specific conductance, SPC). Total removal ranged drastically between bioreactors from 10 to 133 kg N, with removal efficiencies of 9.0% to 62% and N removal rates of 0.21 to 5.36 g N removed per m3 of bioreactor per day. As the first bioreactor study in the humid subtropical coastal plain, this data provides positive proof of concept that denitrifying bioreactor is another tool for reducing N loads in agricultural tile drainage in this region. Full article
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Open AccessArticle Comprehensive Assessment of Regional Water Usage Efficiency Control Based on Game Theory Weight and a Matter-Element Model
Water 2017, 9(2), 113; doi:10.3390/w9020113
Received: 19 October 2016 / Revised: 6 February 2017 / Accepted: 7 February 2017 / Published: 13 February 2017
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Abstract
The efficient control of water usage is one of the core goals of the strictest water resources management system in China. Therefore, the objective and reasonable evaluation of the effects of implementing this system is crucial. Based on the natural and social water
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The efficient control of water usage is one of the core goals of the strictest water resources management system in China. Therefore, the objective and reasonable evaluation of the effects of implementing this system is crucial. Based on the natural and social water cycle theories and the mechanism of the influence of agricultural, industrial, domestic and ecological water utilization, this paper proposes an evaluation index system through the qualitative and quantitative analysis of external and internal factors affecting the efficiency of water usage. Then, a matter-element model is developed on the basis of game theory weight to evaluate the effects of the implementation of efficiency control measures for regional water usage. By calculating the comprehensive correlation, this model can directly indicate the level of regional water use efficiency control. The model is applied to water usage in Jiangxi Province for the period 2011–2014. The results indicate a gradual improvement in the efficiency of water usage in this province. The matter-element extension evaluation model is simple and practical, and the evaluation results are in agreement with the facts. In summary, this method can provide a new theoretical basis for controlling the efficiency of regional water usage. Full article
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Open AccessArticle Increasing the Accuracy of Runoff and Streamflow Simulation in the Nzoia Basin, Western Kenya, through the Incorporation of Satellite-Derived CHIRPS Data
Water 2017, 9(2), 114; doi:10.3390/w9020114
Received: 23 October 2016 / Revised: 24 December 2016 / Accepted: 26 January 2017 / Published: 13 February 2017
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Abstract
Hydrologic models will be an increasingly important tool for water resource managers as water availability dwindles and water security concerns become more pertinent in data-scarce regions. Fortunately, newly available satellite remote sensing technology provides an opportunity for improving the spatial resolution and quality
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Hydrologic models will be an increasingly important tool for water resource managers as water availability dwindles and water security concerns become more pertinent in data-scarce regions. Fortunately, newly available satellite remote sensing technology provides an opportunity for improving the spatial resolution and quality of input data to hydrologic models in such regions. In particular, the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) dataset provides quasi-global high resolution precipitation information derived from a blend of in situ and active and passive remote sensing data sources. We piloted the incorporation of the CHIRPS dataset into the Soil and Water Assessment Tool (SWAT), a hydrologic model. Comparisons of results between estimation of streamflow using in situ rainfall gauge station data, the Climate Forecast System Reanalysis (CFSR) dataset, and the CHIRPS dataset in the data-scarce Nzoia Basin in western Kenya over the temporal range 1990–2000 were reported. Simulated streamflow estimates were poor with rainfall gauge station data but improved significantly with the CFSR and CHIRPS datasets. However, the use of the CHIRPS dataset in comparison with the CFSR dataset provided an improved statistical performance following model calibration with the exception of one streamflow gauge station in higher elevation regions. Overall, the use of the CHIRPS dataset had the greatest linear correlation, relative variability, and normalized bias despite overall average Nash-Sutcliffe Efficiency (NSE) and R2 values. Full article
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Open AccessArticle Hydrologic Response of Climate Change in the Source Region of the Yangtze River, Based on Water Balance Analysis
Water 2017, 9(2), 115; doi:10.3390/w9020115
Received: 5 December 2016 / Revised: 25 January 2017 / Accepted: 8 February 2017 / Published: 13 February 2017
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Abstract
Due to the large amount of water resources stored in glaciers, permafrost, and lakes, the source region of the Yangtze River (SRYR) is of great importance for the overall basin water flow. For this purpose, a state of art review and calculations were
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Due to the large amount of water resources stored in glaciers, permafrost, and lakes, the source region of the Yangtze River (SRYR) is of great importance for the overall basin water flow. For this purpose, a state of art review and calculations were made for the period 1957–2013 using observed hydrological and meteorological data with a water balance approach. Actual evapotranspiration was calculated and validated by empirical formulas. Water storage change analysis was conducted with uncertainty boundaries using a 10-year moving window. Results show that temperature, precipitation, and actual evapotranspiration in the SRYR increased by 0.34 °C, 11.4 mm, and 7.6 mm per decade, respectively (significant at 0.05 probability level). Runoff appears to have increased at a rate of 3.3 mm per decade. The SRYR water storage in total has not changed significantly during the period, although the moving average is mostly below zero. Based on the water balance equation, the increase in calculated evapotranspiration is mainly due to the significantly increasing temperature. This in combination with increasing precipitation leads to a relatively stable water storage during the study period. Correlation analyses show that precipitation dominates runoff during the warm season (May to October), while temperature anomalies dominate the runoff during the cold season (November to April). The influence of temperature on runoff seems to enhance during the winter period. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Decreased Streamflow in the Yellow River Basin, China: Climate Change or Human‐Induced?
Water 2017, 9(2), 116; doi:10.3390/w9020116
Received: 20 October 2016 / Accepted: 30 January 2017 / Published: 13 February 2017
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Abstract
Decreased streamflow of the Yellow River basin has become the subject of considerable concern in recent years due to the critical importance of the water resources of the Yellow River basin for northern China. This study investigates the changing properties and underlying causes
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Decreased streamflow of the Yellow River basin has become the subject of considerable concern in recent years due to the critical importance of the water resources of the Yellow River basin for northern China. This study investigates the changing properties and underlying causes for the decreased streamflow by applying streamflow data for the period 1960 to 2014 to both the Budyko framework and the hydrological modelling techniques. The results indicate that (1) streamflow decreased 21% during the period 1980–2000, and decreased 19% during the period 2000–2014 when compared to 1960–1979; (2) higher precipitation and relative humidity boost streamflow, while maximum/minimum air temperature, solar radiation, wind speed, and the underlying parameter, n, all have the potential to adversely affect them; (3) decreased streamflow is also linked to increased cropland, grass, reservoir, urban land, and water areas and other human activities associated with GDP and population; (4) human activity is the main reason for the decrease of streamflow in the Yellow River basin, with the mean fractional contribution of 73.4% during 1980–2000 and 82.5% during 2001–2014. It is clear that the continuing growth of humaninduced impacts on streamflow likely to add considerable uncertainty to the management of increasingly scarce water resources. Overall, these results provide strong evidence to suggest that human activity is the key factor behind the decreased streamflow in the Yellow River basin. Full article
(This article belongs to the Special Issue Water-Soil-Vegetation Dynamic Interactions in Changing Climate)
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Open AccessArticle Groundwater Level Changes Due to Extreme Weather—An Evaluation Tool for Sustainable Water Management
Water 2017, 9(2), 117; doi:10.3390/w9020117
Received: 5 November 2016 / Revised: 28 January 2017 / Accepted: 8 February 2017 / Published: 14 February 2017
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Abstract
In the past decade, extreme and exceptional droughts have significantly impacted many economic sectors in the US, especially in California, Oklahoma, and Texas. The record drought of 2011–2014 affected almost 90% of Texas areas and 95% of Oklahoma state areas. In 2011 alone,
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In the past decade, extreme and exceptional droughts have significantly impacted many economic sectors in the US, especially in California, Oklahoma, and Texas. The record drought of 2011–2014 affected almost 90% of Texas areas and 95% of Oklahoma state areas. In 2011 alone, around $1.6 billion in agricultural production were lost as a result of drought in Oklahoma, and $7.6 billion in Texas. The agricultural sectors in Oklahoma and Texas rely mainly on groundwater resources from the non-replenishable Ogallala Aquifer in Panhandle and other aquifers around the states. The exceptional droughts of 2011–2014 not only caused meteorologically induced water scarcity (due to low precipitation), but also prompted farmers to overuse groundwater to maintain the imperiled production. Comprehensive studies on groundwater levels, and thus the actual water availability/scarcity across all aquifers in Oklahoma and Texas are still limited. Existing studies are mainly focused on a small number of selected sites or aquifers over a short time span of well monitoring, which does not allow for a holistic geospatial and temporal evaluation of groundwater level variations. This paper aims at addressing those issues with the proposed geospatial groundwater visualization model to assess availability of groundwater resources for agricultural, industrial, and municipal uses both in Oklahoma and Texas in the time frame of 2003–2014. The model is an evaluation tool that can be used by decision-makers for designing sustainable water management practices and by teachers and researchers for educational purposes. Full article
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Open AccessArticle Climate Change Impacts on US Water Quality Using Two Models: HAWQS and US Basins
Water 2017, 9(2), 118; doi:10.3390/w9020118
Received: 22 November 2016 / Revised: 1 February 2017 / Accepted: 7 February 2017 / Published: 14 February 2017
PDF Full-text (12679 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Climate change and freshwater quality are well-linked. Changes in climate result in changes in streamflow and rising water temperatures, which impact biochemical reaction rates and increase stratification in lakes and reservoirs. Using two water quality modeling systems (the Hydrologic and Water Quality System;
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Climate change and freshwater quality are well-linked. Changes in climate result in changes in streamflow and rising water temperatures, which impact biochemical reaction rates and increase stratification in lakes and reservoirs. Using two water quality modeling systems (the Hydrologic and Water Quality System; HAWQS and US Basins), five climate models, and two greenhouse gas (GHG) mitigation policies, we assess future water quality in the continental U.S. to 2100 considering four water quality parameters: water temperature, dissolved oxygen, total nitrogen, and total phosphorus. Once these parameters are aggregated into a water quality index, we find that, while the water quality models differ under the baseline, there is more agreement between future projections. In addition, we find that the difference in national-scale economic benefits across climate models is generally larger than the difference between the two water quality models. Both water quality models find that water quality will more likely worsen in the East than in the West. Under the business-as-usual emissions scenario, we find that climate change is likely to cause economic impacts ranging from 1.2 to 2.3 (2005 billion USD/year) in 2050 and 2.7 to 4.8 in 2090 across all climate and water quality models. Full article
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Open AccessFeature PaperArticle Maximizing Infiltration Rates by Removing Suspended Solids: Results of Demonstration Testing of Riverbed Filtration in Orange County, California †
Water 2017, 9(2), 119; doi:10.3390/w9020119
Received: 1 December 2016 / Revised: 23 January 2017 / Accepted: 3 February 2017 / Published: 14 February 2017
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Abstract
Clogging due to the accumulation of suspended solids is a major constraint that limits the capacity of Orange County Water District’s (OCWD) surface water recharge system. In order to decrease clogging and increase system capacity, OCWD is testing the ability of riverbed filtration
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Clogging due to the accumulation of suspended solids is a major constraint that limits the capacity of Orange County Water District’s (OCWD) surface water recharge system. In order to decrease clogging and increase system capacity, OCWD is testing the ability of riverbed filtration to reduce suspended solids concentrations and improve recharge rates. Riverbed filtration is achieved through a shallow subsurface collector system placed approximately one meter below the surface. Filtered water from the collector system is conveyed by gravity to the receiving recharge basin. Initial results show that riverbed filtration is highly effective in removing suspended solids in the recharge water, which in turn also greatly increases the recharge capacity of the receiving basin. Some other water quality benefits are also achieved. Data collected thus far indicate that it will be cost-effective to use this approach at a larger scale to capture and recharge increased quantities of storm flow obtained from the Santa Ana River. Full article
(This article belongs to the Special Issue Water Quality Considerations for Managed Aquifer Recharge Systems)
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Open AccessFeature PaperArticle From Surface Flow Velocity Measurements to Discharge Assessment by the Entropy Theory
Water 2017, 9(2), 120; doi:10.3390/w9020120
Received: 22 December 2016 / Revised: 31 January 2017 / Accepted: 9 February 2017 / Published: 14 February 2017
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Abstract
A new methodology for estimating the discharge starting from the monitoring of surface flow velocity, usurf, is proposed. The approach, based on the entropy theory, involves the actual location of maximum flow velocity, umax, which may occur below the
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A new methodology for estimating the discharge starting from the monitoring of surface flow velocity, usurf, is proposed. The approach, based on the entropy theory, involves the actual location of maximum flow velocity, umax, which may occur below the water surface (dip phenomena), affecting the shape of velocity profile. The method identifies the two-dimensional velocity distribution in the cross-sectional flow area, just sampling usurf and applying an iterative procedure to estimate both the dip and umax. Five gage sites, for which a large velocity dataset is available, are used as a case study. Results show that the method is accurate in simulating the depth-averaged velocities along the verticals and the mean flow velocity with an error, on average, lower than 12% and 6%, respectively. The comparison with the velocity index method for the estimation of the mean flow velocity using the measured usurf, demonstrates that the method proposed here is more accurate mainly for rivers with a lower aspect ratio where secondary currents are expected. Moreover, the dip assessment is found more representative of the actual location of maximum flow velocity with respect to the one estimated by a different entropy approach. In terms of discharge, the errors do not exceed 3% for high floods, showing the good potentiality of the method to be used for the monitoring of these events. Full article
(This article belongs to the Special Issue Advances in Hydro-Meteorological Monitoring)
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Open AccessArticle The June 2016 Australian East Coast Low: Importance of Wave Direction for Coastal Erosion Assessment
Water 2017, 9(2), 121; doi:10.3390/w9020121
Received: 5 December 2016 / Revised: 24 January 2017 / Accepted: 6 February 2017 / Published: 14 February 2017
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Abstract
In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave heights offshore of Sydney were not exceptional, nearshore wave conditions were such that
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In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave heights offshore of Sydney were not exceptional, nearshore wave conditions were such that beaches experienced some of the worst erosion in 40 years. Hydrodynamic modelling of wave and current behaviour as well as contemporaneous sand transport shows the east to north-east storm wave direction to be the major determinant of erosion magnitude. This arises because of reduced energy attenuation across the continental shelf and the focussing of wave energy on coastal sections not equilibrated with such wave exposure under the prevailing south-easterly wave climate. Narrabeen–Collaroy, a well-known erosion hot spot on Sydney’s Northern Beaches, is shown to be particularly vulnerable to storms from this direction because the destructive erosion potential is amplified by the influence of the local embayment geometry. We demonstrate the magnified erosion response that occurs when there is bi-directionality between an extreme wave event and preceding modal conditions and the importance of considering wave direction in extreme value analyses. Full article
(This article belongs to the Special Issue Sediment Transport in Coastal Waters)
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Open AccessArticle Applicability of Zero-Inflated Models to Fit the Torrential Rainfall Count Data with Extra Zeros in South Korea
Water 2017, 9(2), 123; doi:10.3390/w9020123
Received: 11 December 2016 / Revised: 31 January 2017 / Accepted: 1 February 2017 / Published: 16 February 2017
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Abstract
Several natural disasters occur because of torrential rainfalls. The change in global climate most likely increases the occurrences of such downpours. Hence, it is necessary to investigate the characteristics of the torrential rainfall events in order to introduce effective measures for mitigating disasters
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Several natural disasters occur because of torrential rainfalls. The change in global climate most likely increases the occurrences of such downpours. Hence, it is necessary to investigate the characteristics of the torrential rainfall events in order to introduce effective measures for mitigating disasters such as urban floods and landslides. However, one of the major problems is evaluating the number of torrential rainfall events from a statistical viewpoint. If the number of torrential rainfall occurrences during a month is considered as count data, their frequency distribution could be identified using a probability distribution. Generally, the number of torrential rainfall occurrences has been analyzed using the Poisson distribution (POI) or the Generalized Poisson Distribution (GPD). However, it was reported that POI and GPD often overestimated or underestimated the observed count data when additional or fewer zeros were included. Hence, in this study, a zero-inflated model concept was applied to solve this problem existing in the conventional models. Zero-Inflated Poisson (ZIP) model, Zero-Inflated Generalized Poisson (ZIGP) model, and the Bayesian ZIGP model have often been applied to fit the count data having additional or fewer zeros. However, the applications of these models in water resource management have been very limited despite their efficiency and accuracy. The five models, namely, POI, GPD, ZIP, ZIGP, and Bayesian ZIGP, were applied to the torrential rainfall data having additional zeros obtained from two rain gauges in South Korea, and their applicability was examined in this study. In particular, the informative prior distributions evaluated via the empirical Bayes method using ten rain gauges were developed in the Bayesian ZIGP model. Finally, it was suggested to avoid using the POI and GPD models to fit the frequency of torrential rainfall data. In addition, it was concluded that the Bayesian ZIGP model used in this study provided the most accurate results for the count data having additional zeros. Moreover, it was recommended that the ZIP model could be an alternative from a practical viewpoint, as the Bayesian approach used in this study was considerably complex. Full article
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Open AccessArticle Decoupling Water Consumption and Environmental Impact on Textile Industry by Using Water Footprint Method: A Case Study in China
Water 2017, 9(2), 124; doi:10.3390/w9020124
Received: 23 November 2016 / Revised: 9 February 2017 / Accepted: 9 February 2017 / Published: 15 February 2017
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Abstract
The rapid development of China’s textile industry has led to consumption and pollution of large volumes of water. Therefore, the textile industry has been the focus of water conservation and waste reduction in China’s 13th Five-Year Plan (2016–2020). The premise of sustainable development
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The rapid development of China’s textile industry has led to consumption and pollution of large volumes of water. Therefore, the textile industry has been the focus of water conservation and waste reduction in China’s 13th Five-Year Plan (2016–2020). The premise of sustainable development is to achieve decoupling of economic growth from water consumption and wastewater discharge. In this work, changes in the blue water footprint, grey water footprint, and the total water footprint of the textile industry from 2001 to 2014 were calculated. The relationship between water footprint and economic growth was then examined using the Tapio decoupling model. Furthermore, factors influencing water footprint were determined through logarithmic mean Divisia index (LMDI) method. Results show that the water footprint of China’s textile industry has strongly decoupled for five years (2003, 2006, 2008, 2011, and 2013) and weakly decoupled for four years (2005, 2007, 2009, and 2010). A decoupling trend occurred during 2001–2014, but a steady stage of decoupling had not been achieved yet. Based on the decomposition analysis, the total water footprint mainly increased along with the production scale. On the contrary, technical level is the most important factor in inhibiting the water footprint. In addition, the effect of industrial structure adjustment is relatively weak. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle Nitrates in Groundwater Discharges from the Azores Archipelago: Occurrence and Fluxes to Coastal Waters
Water 2017, 9(2), 125; doi:10.3390/w9020125
Received: 7 November 2016 / Revised: 26 January 2017 / Accepted: 13 February 2017 / Published: 15 February 2017
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Abstract
Groundwater discharge is an important vector of chemical fluxes to the ocean environment, and as the concentration of nutrients is often higher in discharging groundwater, the deterioration of water quality in the receiving environment can be the result. The main objective of the
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Groundwater discharge is an important vector of chemical fluxes to the ocean environment, and as the concentration of nutrients is often higher in discharging groundwater, the deterioration of water quality in the receiving environment can be the result. The main objective of the present paper is to estimate the total NO3 flux to coastal water bodies due to groundwater discharge in the volcanic Azores archipelago (Portugal). Therefore, 78 springs discharging from perched-water bodies have been monitored since 2003, corresponding to cold (mean = 14.9 °C) and low mineralized (47.2–583 µS/cm) groundwater from the sodium-bicarbonate to sodium-chloride water types. A set of 36 wells was also monitored, presenting groundwater with a higher mineralization. The nitrate content in springs range between 0.02 and 37.4 mg/L, and the most enriched samples are associated to the impact of agricultural activities. The total groundwater NO3 flux to the ocean is estimated in the range of 5.23 × 103 to 190.6 × 103 mol/km2/a (∑ = ~523 × 103 mol/km2/a), exceeding the total flux associated to surface runoff (∑ = ~281 × 103 mol/km2/a). In the majority of the islands, the estimated fluxes are higher than runoff fluxes, with the exception of Pico (47.2%), Corvo (46%) and Faial (7.2%). The total N-NO3 flux estimated in the Azores (~118.9 × 103 mol/km2/a) is in the lower range of estimates made in other volcanic islands. Full article
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Open AccessFeature PaperArticle Climate Change Impacts and Water Management Adaptation in Two Mediterranean-Climate Watersheds: Learning from the Durance and Sacramento Rivers
Water 2017, 9(2), 126; doi:10.3390/w9020126
Received: 19 October 2016 / Revised: 9 December 2016 / Accepted: 6 February 2017 / Published: 16 February 2017
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Abstract
Climate change is bringing more risk and uncertainty to water management in the world’s Mediterranean-climate regions. In this paper, we compare two Mediterranean-climate watersheds: the Durance basin in southern France, and the Sacramento River in northern California, USA. For the Durance basin, we
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Climate change is bringing more risk and uncertainty to water management in the world’s Mediterranean-climate regions. In this paper, we compare two Mediterranean-climate watersheds: the Durance basin in southern France, and the Sacramento River in northern California, USA. For the Durance basin, we present new research on climate change impacts on water management, and discuss their implications for potential adaptation responses. For the Sacramento River, we review existing climate data and research on impacts and describe the progress in implementing various adaptation strategies. We find that the Durance and Sacramento—while certainly at different scales—nonetheless share many characteristics, such as a highly variable climate and hydrology, and extensive hydromodification and intense water competition, which will be affected by climate change. Although some issues and approaches to adaptation are unique to each region, at the same time, these two river basins are utilizing some similar strategies to cope with a changing climate, such as regional planning and management and water conservation. Full article
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Open AccessArticle Restoration of Eutrophic Lakes with Fluctuating Water Levels: A 20-Year Monitoring Study of Two Inter-Connected Lakes
Water 2017, 9(2), 127; doi:10.3390/w9020127
Received: 5 September 2016 / Revised: 8 February 2017 / Accepted: 9 February 2017 / Published: 16 February 2017
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Abstract
Eutrophication continues to be the most important problem preventing a favorable environmental state and detrimentally impacting the ecosystem services of lakes. The current study describes the results of analyses of 20 year monitoring data from two interconnected Anatolian lakes, Lakes Mogan and Eymir,
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Eutrophication continues to be the most important problem preventing a favorable environmental state and detrimentally impacting the ecosystem services of lakes. The current study describes the results of analyses of 20 year monitoring data from two interconnected Anatolian lakes, Lakes Mogan and Eymir, receiving sewage effluents and undergoing restoration. The first step of restoration in both lakes was sewage effluent diversion. Additionally, in hypertrophic Lake Eymir, biomanipulation was conducted, involving removal of benthi-planktivorous fish and prohibition of pike fishing. The monitoring period included high (H) and low (L) water levels (WL) enabling elucidation of the effects of hydrological changes on lake restoration. In shallower Lake Mogan, macrophyte abundance increased after the sewage effluent diversion in periods with low water levels even at turbid water. In comparatively deeper Lake Eymir, the first biomanipulation led to a clear water state with abundant macrophyte coverage. However, shortly after biomanipulation, the water clarity declined, coinciding with low water level (LWL) periods during which nutrient concentrations increased. A second biomanipulation was conducted, mostly during high water level (HWL) period, resulting in a major decrease in nutrient concentrations and clearer water, but without an expansion of macrophytes. We conclude that repetitive fish removal may induce recovery but its success may be confounded by high availability of nutrients and adverse hydrological conditions. Full article
(This article belongs to the Special Issue Lake Restoration and Management in a Climate Change Perspective)
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Open AccessArticle Valuing Multiple Benefits, and the Public Perception of SUDS Ponds
Water 2017, 9(2), 128; doi:10.3390/w9020128
Received: 2 December 2016 / Revised: 7 February 2017 / Accepted: 9 February 2017 / Published: 16 February 2017
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Abstract
Understanding how the public perceive and value ponds is fundamental to appreciate the synergy between Sustainable urban Drainage (SUDS) ponds and the multiple benefits they provide. This paper investigates this, through the application of a structured postal and online survey, for a case
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Understanding how the public perceive and value ponds is fundamental to appreciate the synergy between Sustainable urban Drainage (SUDS) ponds and the multiple benefits they provide. This paper investigates this, through the application of a structured postal and online survey, for a case study area of Edinburgh, in the UK. It compares man-made ponds (including SUDS), and ponds with natural origins. The results from Whole Life Cost show that the benefits (based on Contingent Valuation) exceed the CAPEX and OPEX costs for three of five artificial ponds studied. Benefits from natural (reference) ponds exceed the replacement costs for a pond with the same surface area/catchment. This paper highlights the importance of monetising the multiple benefits from ponds. Full article
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Open AccessArticle Structuring Climate Adaptation through Multiple Perspectives: Framework and Case Study on Flood Risk Management
Water 2017, 9(2), 129; doi:10.3390/w9020129
Received: 24 September 2016 / Revised: 2 February 2017 / Accepted: 4 February 2017 / Published: 19 February 2017
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Abstract
Adaptation to climate change is being addressed in many domains. This means that there are multiple perspectives on adaptation; often with differing visions resulting in disconnected responses and outcomes. Combining singular perspectives into coherent, combined perspectives that include multiple needs and visions can
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Adaptation to climate change is being addressed in many domains. This means that there are multiple perspectives on adaptation; often with differing visions resulting in disconnected responses and outcomes. Combining singular perspectives into coherent, combined perspectives that include multiple needs and visions can help to deepen the understanding of various aspects of adaptation and provide more effective responses. Such combinations of perspectives can help to increase the range and variety of adaptation measures available for implementation or avoid maladaptation compared with adaptations derived from a singular perspective. The objective of this paper is to present and demonstrate a framework for structuring the local adaptation responses using the inputs from multiple perspectives. The adaptation response framing has been done by: (i) contextualizing climate change adaptation needs; (ii) analyzing drivers of change; (iii) characterizing measures of adaptation; and (iv) establishing links between the measures with a particular emphasis on taking account of multiple perspectives. This framework was demonstrated with reference to the management of flood risks in a case study Can Tho, Vietnam. The results from the case study show that framing of adaptation responses from multiple perspectives can enhance the understanding of adaptation measures, thereby helping to bring about more flexible implementation practices. Full article
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Open AccessFeature PaperArticle Where There Is No History: How to Create Trust and Connection in Learning for Transformation in Water Governance
Water 2017, 9(2), 130; doi:10.3390/w9020130
Received: 3 October 2016 / Revised: 11 January 2017 / Accepted: 11 February 2017 / Published: 19 February 2017
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Abstract
Trust is often seen as an important element in settings of knowledge sharing and the co-creation of knowledge for dealing with transformations in water governance. However, seemingly similar conversations during a co-creation workshop in Uppsala resulted in both trust and distrust, and thereby
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Trust is often seen as an important element in settings of knowledge sharing and the co-creation of knowledge for dealing with transformations in water governance. However, seemingly similar conversations during a co-creation workshop in Uppsala resulted in both trust and distrust, and thereby influenced consequent possibilities for the co-creation of knowledge. Therefore, this article focuses on how trust influences knowledge sharing and how knowledge sharing influences trust. We use a case study approach to analyze the Uppsala co-creation workshop—part of the Climate Change Adaptation and Water Governance (CADWAGO) project—by comparing 25 conversations, making use of theories on swift trust and trust dynamics. We found four different conversation patterns (1) sending; (2) defending; (3) misunderstanding; and (4) connecting. The first three patterns influenced trust negatively and did not lead to knowledge sharing, whereas pattern four showed trust development and co-creation of knowledge. From our comparative analyses, we conclude that trust starts to emerge when there is mutual openness and empathy visible in turn-taking patterns. More specifically, trust emerges when communication styles allow for recognition and exploring underlying needs and wishes, resulting in a more dynamic dialogue, further trust development, and connection between actors. Our list of conversation patterns is provisional but we argue that understanding how different kinds of interactions can lead to trust or distrust is crucial to understanding why and how learning takes place—insights that are essential for fostering learning and transformations in water governance. Full article
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Open AccessArticle Modelling Dissolved Oxygen/Sediment Oxygen Demand under Ice in a Shallow Eutrophic Prairie Reservoir
Water 2017, 9(2), 131; doi:10.3390/w9020131
Received: 17 December 2016 / Revised: 9 February 2017 / Accepted: 10 February 2017 / Published: 17 February 2017
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Abstract
Dissolved oxygen is an influential factor of aquatic ecosystem health. Future predictions of oxygen deficits are paramount for maintaining water quality. Oxygen demands depend greatly on a waterbody’s attributes. A large sediment–water interface relative to volume means sediment oxygen demand has greater influence
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Dissolved oxygen is an influential factor of aquatic ecosystem health. Future predictions of oxygen deficits are paramount for maintaining water quality. Oxygen demands depend greatly on a waterbody’s attributes. A large sediment–water interface relative to volume means sediment oxygen demand has greater influence in shallow systems. In shallow, ice-covered waterbodies the potential for winter anoxia is high. Water quality models offer two options for modelling sediment oxygen demand: a zero-order constant rate, or a sediment diagenesis model. The constant rate is unrepresentative of a real system, yet a diagenesis model is difficult to parameterise and calibrate without data. We use the water quality model CE-QUAL-W2 to increase the complexity of a zero-order sediment compartment with limited data. We model summer and winter conditions individually to capture decay rates under-ice. Using a semi-automated calibration method, we find an annual pattern in sediment oxygen demand that follows the trend of chlorophyll-a concentrations in a shallow, eutrophic Prairie reservoir. We use chlorophyll-a as a proxy for estimation of summer oxygen demand and winter decay. We show that winter sediment oxygen demand is dependent on the previous summer’s maximum chlorophyll-a concentrations. Full article
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Open AccessArticle SPH Simulations of Solute Transport in Flows with Steep Velocity and Concentration Gradients
Water 2017, 9(2), 132; doi:10.3390/w9020132
Received: 7 December 2016 / Revised: 6 February 2017 / Accepted: 14 February 2017 / Published: 17 February 2017
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Abstract
In this study, a meshless particle method, smoothed particle hydrodynamics (SPH), is adopted to solve the shallow water equations (SWEs) and the advection diffusion equations (ADEs) for simulating solute transport processes under 1D/2D conditions with steep gradients. A new SPH-SWEs-ADEs model is herein
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In this study, a meshless particle method, smoothed particle hydrodynamics (SPH), is adopted to solve the shallow water equations (SWEs) and the advection diffusion equations (ADEs) for simulating solute transport processes under 1D/2D conditions with steep gradients. A new SPH-SWEs-ADEs model is herein developed to focus on the numerical performance of solute transport in flows with steep velocity and concentration gradients, since the traditional mesh-based methods have numerical difficulties on solving such steep velocity/concentration gradient flows. The present model is validated by six benchmark study cases, including three steep concentration gradient cases and three coupled steep concentration/velocity gradient cases. The comparison between the simulated results and the exact solutions for the former three cases shows that complete mass concentration conservation in pure advection-dominated flows is preserved. The numerical oscillation in concentration and the negative concentration resulted from the discretization of the advection term of ADEs can be totally avoided. The other three cases confirm that this model can also well capture coupled steep gradients of velocities and concentrations. It is demonstrated that the presented solver is an effective and reliable tool to investigate solute transports in complex flows incorporating steep velocity gradients. Full article
(This article belongs to the Special Issue Modeling of Water Systems)
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Open AccessArticle Quantifying River Channel Stability at the Basin Scale
Water 2017, 9(2), 133; doi:10.3390/w9020133
Received: 1 January 2017 / Accepted: 15 February 2017 / Published: 17 February 2017
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Abstract
This paper examines the feasibility of a basin‐scale scheme for characterising and quantifying river reaches in terms of their geomorphological stability status and potential for morphological adjustment based on auditing stream energy. A River Energy Audit Scheme (REAS) is explored, which involves integrating
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This paper examines the feasibility of a basin‐scale scheme for characterising and quantifying river reaches in terms of their geomorphological stability status and potential for morphological adjustment based on auditing stream energy. A River Energy Audit Scheme (REAS) is explored, which involves integrating stream power with flow duration to investigate the downstream distribution of Annual Geomorphic Energy (AGE). This measure represents the average annual energy available with which to perform geomorphological work in reshaping the channel boundary. Changes in AGE between successive reaches might indicate whether adjustments are likely to be led by erosion or deposition at the channel perimeter. A case study of the River Kent in Cumbria, UK, demonstrates that basin‐wide application is achievable without excessive field work and data processing. However, in addressing the basin scale, the research found that this is inevitably at the cost of a number of assumptions and limitations, which are discussed herein. Technological advances in remotely sensed data capture, developments in image processing and emerging GIS tools provide the near‐term prospect of fully quantifying river channel stability at the basin scale, although as yet not fully realized. Potential applications of this type of approach include system‐wide assessment of river channel stability and sensitivity to land‐use or climate change, and informing strategic planning for river channel and flood risk management. Full article
(This article belongs to the Special Issue Stream Channel Stability, Assessment, Modeling, and Mitigation)
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Open AccessArticle Effective Saturated Hydraulic Conductivity for Representing Field-Scale Infiltration and Surface Soil Moisture in Heterogeneous Unsaturated Soils Subjected to Rainfall Events
Water 2017, 9(2), 134; doi:10.3390/w9020134
Received: 16 December 2016 / Revised: 9 February 2017 / Accepted: 13 February 2017 / Published: 20 February 2017
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Abstract
Spatial heterogeneity in soil properties has been a challenge for providing field-scale estimates of infiltration rates and surface soil moisture content over natural fields. In this study, we develop analytical expressions for effective saturated hydraulic conductivity for use with the Green-Ampt model to
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Spatial heterogeneity in soil properties has been a challenge for providing field-scale estimates of infiltration rates and surface soil moisture content over natural fields. In this study, we develop analytical expressions for effective saturated hydraulic conductivity for use with the Green-Ampt model to describe field-scale infiltration rates and evolution of surface soil moisture over unsaturated fields subjected to a rainfall event. The heterogeneity in soil properties is described by a log-normal distribution for surface saturated hydraulic conductivity. Comparisons between field-scale numerical and analytical simulation results for water movement in heterogeneous unsaturated soils show that the proposed expressions reproduce the evolution of surface soil moisture and infiltration rate with time. The analytical expressions hold promise for describing mean field infiltration rates and surface soil moisture evolution at field-scale over sandy loam and loamy sand soils. Full article
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Open AccessArticle Accessing the Difference in the Climate Elasticity of Runoff across the Poyang Lake Basin, China
Water 2017, 9(2), 135; doi:10.3390/w9020135
Received: 30 August 2016 / Revised: 9 February 2017 / Accepted: 11 February 2017 / Published: 20 February 2017
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Abstract
Understanding the effects of climate and catchment properties’ changes on water yield is a challenging component in assessments of future water resources. Here, we spatially applied the water-energy balance equation, based on the widely-used Budyko framework, to quantify the temporal and spatial differences
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Understanding the effects of climate and catchment properties’ changes on water yield is a challenging component in assessments of future water resources. Here, we spatially applied the water-energy balance equation, based on the widely-used Budyko framework, to quantify the temporal and spatial differences of the climate elasticity of runoff in the Poyang Lake Basin (PYLB), highlighting the influence of the catchment properties’ parameter n variation on the climate elasticity and runoff prediction. By using Sen’s slope and the Mann–Kendall method, we found that, for the whole study period (1960–2010), annual temperature in PYLB significantly increased at a rate of 1.44% per decade. Basin-wide wind speed and net radiation had been declining at 0.17 m/s and 46.30 MJ/m2 per decade. No significant trend was detected in precipitation and relative humidity. The moving average method was applied to evaluate the temporal pattern of n. The results showed that the calibrated catchment properties’ parameter and the derived elasticities were not constant during the past 50 years. We found that in most sub-basins, the n values increased during 1970–1980, followed by a decreasing trend in the period from 1980 to 1990, whereas the n value in Fuhe sub-basin kept increasing for the almost the whole study period. In addition, the climate elasticity is highly correlated with the n value, indicating that the catchment properties’ parameter was the dominant factor influencing climate elasticity in PYLB in the past 50 years. We also attempted to predict the runoff trend with the consideration of trends in n. However, in some sub-basins, there were still considerable differences between the predicted runoff trend and the observed one. The method used here to evaluate the temporal pattern of n should be an extension of the existing literature and will provide a better understanding of elasticity in the regional hydrological cycle. Full article
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Open AccessArticle Agricultural Irrigation Water Use in a Closed Basin and the Impacts on Water Productivity: The Case of the Guadalquivir River Basin (Southern Spain)
Water 2017, 9(2), 136; doi:10.3390/w9020136
Received: 15 November 2016 / Accepted: 13 February 2017 / Published: 20 February 2017
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Abstract
This paper analyses the agricultural irrigation water use in a closed basin and the impacts on water productivity, and examines how they have affected the ‘closure’ process of the Guadalquivir river basin observed in recent decades. Following a period of expansion in irrigation,
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This paper analyses the agricultural irrigation water use in a closed basin and the impacts on water productivity, and examines how they have affected the ‘closure’ process of the Guadalquivir river basin observed in recent decades. Following a period of expansion in irrigation, an administrative moratorium was declared on new irrigated areas in 2005. Since then, the main policy measure has been aimed at the modernisation of irrigated agriculture and the implementation of water conservation technologies. The analysis carried out in this paper shows a significant increase in mean irrigation water productivity in the pre‐moratorium period (1989–2005), driven by the creation of new irrigated areas devoted to high value crops and with a dominant use of deficit irrigation strategies, while a second phase (2005–2012) is characterised by slower growth in terms of the mean productivity of irrigation water, primarily as a result of a significant reduction in water use per area. Findings show that productivity gains seem to have reached a ceiling in this river basin, since technological innovations (such as new crops, deficit irrigation, and water‐saving and conservation technologies) have reached the limits of their capacity to create new value. Full article
(This article belongs to the Special Issue Water Economics and Policy)
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Open AccessArticle Tracer Experiments and Hydraulic Performance Improvements in a Treatment Pond
Water 2017, 9(2), 137; doi:10.3390/w9020137
Received: 17 November 2016 / Accepted: 14 February 2017 / Published: 20 February 2017
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Abstract
The treatment efficiency of a wetland constructed for nutrient removal depends strongly on the flow patterns and residence times of the wetland. In this study, a tracer experiment was performed to estimate the residence time distribution and the hydraulic efficiency of a treatment
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The treatment efficiency of a wetland constructed for nutrient removal depends strongly on the flow patterns and residence times of the wetland. In this study, a tracer experiment was performed to estimate the residence time distribution and the hydraulic efficiency of a treatment pond with shallow and deep‐water areas. Rhodamine WT experiments revealed a non‐uniform flow pattern in the deep‐water area and an overall poor hydraulic efficiency in the wetland. To improve flow uniformity and hydraulic efficiency, several design options for different inlet-outlet configurations, flow rates, water depths, and emergent baffle additions were considered. The effects on hydraulic performance were investigated through mathematical model simulations. The results revealed that increasing the flow rate and decreasing the water depth slightly improved the hydraulic performance, whereas changing the positions of the inlet and outlet produced inconsistent effects. The most effective improvement involved installing emergent baffles, with the number of baffles presenting the largest positive effect, followed by the width and length of the baffles. Long and thin baffles resulted in a uniform flow velocity field, a meandering flow path, and greater residence times and effective volume ratios. The installation of two baffles increased the hydraulic efficiency to 1.00, indicating excellent hydraulic performance. The thin baffles occupied approximately 3.7%-6.3% of the deep‐water area and 1.9%-3.2% of the entire pond, indicating the potential for their practical application in limited land use regions. Full article
(This article belongs to the Special Issue Treatment Wetlands for Nutrient Removal)
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Open AccessArticle Raw Water Quality and Pretreatment in Managed Aquifer Recharge for Drinking Water Production in Finland
Water 2017, 9(2), 138; doi:10.3390/w9020138
Received: 12 January 2017 / Accepted: 10 February 2017 / Published: 20 February 2017
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Abstract
The main objective of managed aquifer recharge (MAR) in Finland is the removal of natural organic matter (NOM) from surface waters. A typical MAR procedure consists of the infiltration of surface water into a Quaternary glaciofluvial esker with subsequent withdrawal of the MAR
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The main objective of managed aquifer recharge (MAR) in Finland is the removal of natural organic matter (NOM) from surface waters. A typical MAR procedure consists of the infiltration of surface water into a Quaternary glaciofluvial esker with subsequent withdrawal of the MAR treated water from wells a few hundred meters downstream. The infiltrated water should have a residence time of at least approximately one month before withdrawal to provide sufficient time for the subsurface processes needed to break down or remove humic substances. Most of the Finnish MAR plants do not have pretreatment and raw water is infiltrated directly into the soil. The objectives of this paper are to present MAR experiences and to discuss the need for and choice of pretreatment. Data from basin, sprinkling, and well infiltration processes are presented. Total organic carbon (TOC) concentrations of the raw waters presented here varied from 6.5 to 11 mg/L and after MAR the TOC concentrations of the abstracted waters were approximately 2 mg/L. The overall reduction of organic matter in the treatment (with or without pretreatment) was 70%-85%. Mechanical pretreatment can be used for clogging prevention. Turbidity of the Finnish lakes used as raw water does not necessitate pretreatment in basin and sprinkling infiltration, however, pretreatment in well infiltration needs to be judged separately. River waters may have high turbidity requiring pretreatment. Biodegradation of NOM in the saturated groundwater zone consumes dissolved oxygen. Thus, a high NOM concentration may create conditions for dissolution of iron and manganese from the soil. These conditions may be avoided by the addition of chemical pretreatment. Raw waters with TOC content up to at least approximately 8 mg/L were infiltrated without any considerations of chemical pretreatment, which should be evaluated based on local conditions. Full article
(This article belongs to the Special Issue Water Quality Considerations for Managed Aquifer Recharge Systems)
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Open AccessArticle Could Changing Power Relationships Lead to Better Water Sharing in Central Asia?
Water 2017, 9(2), 139; doi:10.3390/w9020139
Received: 7 December 2016 / Accepted: 16 February 2017 / Published: 20 February 2017
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Abstract
Even though Central Asia is water rich, water disputes have characterized the region after crumbling of the Soviet Union in 1991. The uneven spatial distribution and complex pattern of transboundary water sources with contrasting national water needs have created an intricate water dilemma.
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Even though Central Asia is water rich, water disputes have characterized the region after crumbling of the Soviet Union in 1991. The uneven spatial distribution and complex pattern of transboundary water sources with contrasting national water needs have created an intricate water dilemma. Increasing national water needs, water claims by surrounding countries, uncertainties in renewable water volumes, and effects of climate change will put further strain on the future water use in Central Asia. We argue that the present power distribution with three downstream hegemons (Kazakhstan, Turkmenistan, and Uzbekistan) and two upstream much poorer countries with less political influence (Kyrgyzstan and Tajikistan) is not likely to lead forward to a greater willingness to share water. We discuss this situation with the analogue Egypt-Sudan-Ethiopia in the Nile Basin. Thus, as in the case of Ethiopia in the Nile Basin, gradually economically stronger upstream countries Kyrgyzstan and Tajikistan due to hydropower development are likely to eventually re-define the hydropolitical map of Central Asia. As in the case of the Nile Basin, a more even power balance between upstream and downstream countries may lead to an improved political structure for a much-needed better collaboration on water issues. Full article
(This article belongs to the Special Issue The Future of Water Management in Central Asia)
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Open AccessArticle Soil Moisture for Hydrological Applications: Open Questions and New Opportunities
Water 2017, 9(2), 140; doi:10.3390/w9020140
Received: 10 January 2017 / Accepted: 15 February 2017 / Published: 20 February 2017
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Abstract
Soil moisture is widely recognized as a key parameter in the mass and energy balance between the land surface and the atmosphere and, hence, the potential societal benefits of an accurate estimation of soil moisture are immense. Recently, scientific community is making great
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Soil moisture is widely recognized as a key parameter in the mass and energy balance between the land surface and the atmosphere and, hence, the potential societal benefits of an accurate estimation of soil moisture are immense. Recently, scientific community is making great effort for addressing the estimation of soil moisture over large areas through in situ sensors, remote sensing and modelling approaches. The different techniques used for addressing the monitoring of soil moisture for hydrological applications are briefly reviewed here. Moreover, some examples in which in situ and satellite soil moisture data are successfully employed for improving hydrological monitoring and predictions (e.g., floods, landslides, precipitation and irrigation) are presented. Finally, the emerging applications, the open issues and the future opportunities given by the increased availability of soil moisture measurements are outlined. Full article
(This article belongs to the Special Issue Advances in Hydro-Meteorological Monitoring)
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Open AccessArticle Water Leakage and Nitrate Leaching Characteristics in the Winter Wheat–Summer Maize Rotation System in the North China Plain under Different Irrigation and Fertilization Management Practices
Water 2017, 9(2), 141; doi:10.3390/w9020141
Received: 16 October 2016 / Revised: 11 January 2017 / Accepted: 14 February 2017 / Published: 22 February 2017
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Abstract
Field experiments were carried out in Huantai County from 2006 to 2008 to evaluate the effects of different nitrogen (N) fertilization and irrigation management practices on water leakage and nitrate leaching in the dominant wheat–maize rotation system in the North China Plain (NCP).
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Field experiments were carried out in Huantai County from 2006 to 2008 to evaluate the effects of different nitrogen (N) fertilization and irrigation management practices on water leakage and nitrate leaching in the dominant wheat–maize rotation system in the North China Plain (NCP). Two N fertilization (NF1, the traditional one; NF2, fertilization based on soil testing) and two irrigation (IR1, the traditional one; IR2, irrigation based on real-time soil water content monitoring) management practices were designed in the experiments. Water and nitrate amounts leaving the soil layer at a depth of 2.0 m below the soil surface were calculated and compared. Results showed that the IR2 effectively reduced water leakage and nitrate leaching amounts in the two-year period, especially in the winter wheat season. Less than 10 percent irrigation water could be saved in a dry winter wheat season, but about 60 percent could be saved in a wet winter wheat season. Besides, 58.8 percent nitrate under single NF2IR1 and 85.2 percent under NF2IR2 could be prevented from leaching. The IR2 should be considered as the best management practice to save groundwater resources and prevent nitrate from leaching. The amounts of N input play a great role in affecting nitrate concentrations in the soil solutions in the winter wheat–summer maize rotation system. The NF2 significantly reduced N inputs and should be encouraged in ordinary agricultural production. Thus, nitrate leaching and groundwater contamination could be alleviated, but timely N supplement might be needed under high precipitation condition. Full article
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Open AccessArticle Geographic Distribution of Registered Packaged Water Production in Ghana: Implications for Piped Supplies, Groundwater Management and Product Transportation
Water 2017, 9(2), 142; doi:10.3390/w9020142
Received: 9 December 2016 / Accepted: 16 February 2017 / Published: 21 February 2017
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Abstract
Packaged water consumption has grown rapidly in urban areas of many low‐income and middle‐income countries, but particularly in Ghana. However, the sources of water used by this growing packaged water industry and the implications for water resource management and transport‐related environmental impacts have
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Packaged water consumption has grown rapidly in urban areas of many low‐income and middle‐income countries, but particularly in Ghana. However, the sources of water used by this growing packaged water industry and the implications for water resource management and transport‐related environmental impacts have not been described. This study aimed to assess the spatial distribution of regulated packaged water production in Ghana, both in relation to demand for natural mineral water and hydrogeological characteristics. A total of 764 addresses for premises licensed to produce packaged water from 2009 to 2015 were mapped and compared to regional sachet water consumption and examined beverage import/export data. We found evidence to suggest that packaged water is transported shorter distances in Ghana than in developed countries. Groundwater abstraction for packaged water is low relative to piped water production and domestic borehole abstraction nationally, but may be locally significant. For natural mineral water, producers should be able to address the most widespread water quality hazards (including high salinity, iron and nitrates) in aquifers used for production through reverse osmosis treatment. In future, packaged water producer surveys could be used to quantify unregulated production, volumes of piped versus groundwater abstracted and treatment processes used. Full article
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Open AccessArticle Automated Extraction of Urban Water Bodies from ZY‐3 Multi‐Spectral Imagery
Water 2017, 9(2), 144; doi:10.3390/w9020144
Received: 31 October 2016 / Accepted: 14 February 2017 / Published: 21 February 2017
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Abstract
The extraction of urban water bodies from high‐resolution remote sensing images, which has been a hotspot in researches, has drawn a lot of attention both domestic and abroad. A challenging issue is to distinguish the shadow of high‐rise buildings from water bodies. To
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The extraction of urban water bodies from high‐resolution remote sensing images, which has been a hotspot in researches, has drawn a lot of attention both domestic and abroad. A challenging issue is to distinguish the shadow of high‐rise buildings from water bodies. To tackle this issue, we propose the automatic urban water extraction method (AUWEM) to extract urban water bodies from high‐resolution remote sensing images. First, in order to improve the extraction accuracy, we refine the NDWI algorithm. Instead of Band2 in NDWI, we select the first principal component after PCA transformation as well as Band1 for ZY‐3 multi‐spectral image data to construct two new indices, namely NNDWI1, which is sensitive to turbid water, and NNDWI2, which is sensitive to the water body whose spectral information is interfered by vegetation. We superimpose the image threshold segmentation results generated by applying NNDWI1 and NNDWI2, then detect and remove the shadows in the small areas of the segmentation results using object‐oriented shadow detection technology, and finally obtain the results of the urban water extraction. By comparing the Maximum Likelihood Method (MaxLike) and NDWI, we find that the average Kappa coefficients of AUWEM, NDWI and MaxLike in the five experimental areas are about 93%, 86.2% and 88.6%, respectively. AUWEM exhibits lower omission error rates and commission error rates compared with the NDWI and MaxLike. The average total error rates of the three methods are about 11.9%, 18.2%, and 22.1%, respectively. AUWEM not only shows higher water edge detection accuracy, but it also is relatively stable with the change of threshold. Therefore, it can satisfy demands of extracting water bodies from ZY‐3 images. Full article
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Open AccessArticle Developing Intensity–Duration–Frequency (IDF) Curves under Climate Change Uncertainty: The Case of Bangkok, Thailand
Water 2017, 9(2), 145; doi:10.3390/w9020145
Received: 8 December 2016 / Revised: 10 February 2017 / Accepted: 15 February 2017 / Published: 22 February 2017
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Abstract
The magnitude and frequency of hydrological events are expected to increase in coming years due to climate change in megacities of Asia. Intensity–Duration–Frequency (IDF) curves represent essential means to study effects on the performance of drainage systems. Therefore, the need for updating IDF
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The magnitude and frequency of hydrological events are expected to increase in coming years due to climate change in megacities of Asia. Intensity–Duration–Frequency (IDF) curves represent essential means to study effects on the performance of drainage systems. Therefore, the need for updating IDF curves comes from the necessity to gain better understanding of climate change effects. The present paper explores an approach based on spatial downscaling-temporal disaggregation method (DDM) to develop future IDFs using stochastic weather generator, Long Ashton Research Station Weather Generator (LARS-WG) and the rainfall disaggregation tool, Hyetos. The work was carried out for the case of Bangkok, Thailand. The application of LARS-WG to project extreme rainfalls showed promising results and nine global climate models (GCMs) were used to estimate changes in IDF characteristics for future time periods of 2011–2030 and 2046–2065 under climate change scenarios. The IDFs derived from this approach were corrected using higher order equation to mitigate biases. IDFs from all GCMs showed increasing intensities in the future for all return periods. The work presented demonstrates the potential of this approach in projecting future climate scenarios for urban catchment where long term hourly rainfall data are not readily available. Full article
(This article belongs to the Special Issue Hydroinformatics and Urban Water Systems)
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Open AccessFeature PaperArticle Where to Find Water Pipes and Sewers?—On the Correlation of Infrastructure Networks in the Urban Environment
Water 2017, 9(2), 146; doi:10.3390/w9020146
Received: 14 December 2016 / Accepted: 16 February 2017 / Published: 21 February 2017
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Abstract
Urban water infrastructure, i.e., water supply and sewer networks, are underground structures, implying that detailed information on their location and features is not directly accessible, frequently erroneous, or missing. For public use, data is also not made available due to security concerns. This
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Urban water infrastructure, i.e., water supply and sewer networks, are underground structures, implying that detailed information on their location and features is not directly accessible, frequently erroneous, or missing. For public use, data is also not made available due to security concerns. This lack of quality data, especially for research purposes, requires substantial effort when such data is sought for both statistical and model‐based analyses. An alternative to gathering data from archives and observations is to extract the information from surrogate data sources (e.g., the street network). The key for such an undertaking is to identify the common characteristics of all urban infrastructure network types and to quantify them. In this work, the network correlations of the street, water supply, and sewer networks are systematically analyzed. The results showed a strong correlation between the street networks and urban water infrastructure networks, in general. For the investigated cases, on average, 50% of the street network length correlates with 80%-85% of the total water supply/sewer network. A correlation between street types and water infrastructure properties (e.g., pipe diameter) cannot be found. All analyses are quantified in the form of different geometric‐ and graph‐based indicators. The obtained results improve the understanding of urban network infrastructure from an integrated point of view. Moreover, the method can be fundamental for different research purposes, such as data verification, data completion, or even the entire generation of feasible datasets. Full article
(This article belongs to the Special Issue Synergies in Urban Water Infrastructure Modeling)
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Open AccessArticle Modeling Rainfall-Runoff Response to Land Use and Land Cover Change in Rwanda (1990–2016)
Water 2017, 9(2), 147; doi:10.3390/w9020147
Received: 29 December 2016 / Revised: 7 February 2017 / Accepted: 14 February 2017 / Published: 22 February 2017
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Abstract
Stormwater runoff poses serious environmental problems and public health issues in Rwanda, a tropical country that is increasingly suffering from severe floods, landslides, soil erosion and water pollution. Using the WetSpa Extension model, this study assessed the changes in rainfall runoff depth in
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Stormwater runoff poses serious environmental problems and public health issues in Rwanda, a tropical country that is increasingly suffering from severe floods, landslides, soil erosion and water pollution. Using the WetSpa Extension model, this study assessed the changes in rainfall runoff depth in Rwanda from 1990 to 2016 in response to precipitation and land use changes. Our results show that Rwanda has experienced a significant conversion of natural forest and grassland to cropland and built-up areas. During the period 1990–2016, 7090.02 km2 (64.5%) and 1715.26 km2 (32.1%) of forest and grassland covers were lost, respectively, while the cropland and built-up areas increased by 135.3% (8503.75 km2) and 304.3% (355.02 km2), respectively. According to our estimates, the land use change effect resulted in a national mean runoff depth increase of 2.33 mm/year (0.38%). Although precipitation change affected the inter-annual fluctuation of runoff, the long-term trend of runoff was dominated by land use change. The top five districts that experienced the annual runoff depth increase (all >3.8 mm/year) are Rubavu, Nyabihu, Ngororero, Gakenke, and Musanze. Their annual runoff depths increased at a rate of >3.8 mm/year during the past 27 years, due to severe deforestation (ranging from 62% to 85%) and cropland expansion (ranging from 123% to 293%). These areas require high priority in runoff control using terracing in croplands and rainwater harvesting systems such as dam/reservoirs, percolation tanks, storage tanks, etc. The wet season runoff was three times higher than the dry season runoff in Rwanda; appropriate rainwater management and reservation could provide valuable irrigation water for the dry season or drought years (late rainfall onsets or early rainfall cessations). It was estimated that a reservation of 30.5% (3.99 km3) of the runoff in the wet season could meet the cropland irrigation water gap during the dry season in 2016. Full article
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Open AccessArticle Improvements to Runoff Predictions from a Land Surface Model with a Lateral Flow Scheme Using Remote Sensing and In Situ Observations
Water 2017, 9(2), 148; doi:10.3390/w9020148
Received: 30 December 2016 / Revised: 25 January 2017 / Accepted: 20 February 2017 / Published: 22 February 2017
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Abstract
Like most land surface models (LSMs) coupled to regional climate models (RCMs), the original Common Land Model (CoLM) predicts runoff from net water at each computational grid without explicit lateral flow (LF) schemes. This study has therefore proposed a CoLM+LF model incorporating a
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Like most land surface models (LSMs) coupled to regional climate models (RCMs), the original Common Land Model (CoLM) predicts runoff from net water at each computational grid without explicit lateral flow (LF) schemes. This study has therefore proposed a CoLM+LF model incorporating a set of lateral surface and subsurface runoff computations controlled by topography into the existing terrestrial hydrologic processes in the CoLM to improve runoff predictions in land surface parameterizations. This study has assessed the new CoLM+LF using Earth observations at the 30-km resolution targeted for mesoscale climate applications, especially for surface and subsurface runoff predictions in the Nakdong River Watershed of Korea under study. Both the baseline CoLM and the new CoLM+LF are implemented in a standalone mode using the realistic surface boundary conditions (SBCs) and meteorological forcings constructed from remote sensing products and in situ observations, mainly by geoprocessing tools in a Geographic Information System (GIS) for the study domain. The performance of the CoLM and the CoLM+LF simulations are evaluated by the comparison of daily runoff results from both models with observations during 2009 at the Jindong stream gauge station in the study watershed. The proposed CoLM+LF, which can simulate the effect of runoff travel time over a watershed by an explicit lateral flow scheme, more effectively captures seasonal variations in daily streamflow than the baseline CoLM. Full article
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Open AccessArticle Using SWAT and Fuzzy TOPSIS to Assess the Impact of Climate Change in the Headwaters of the Segura River Basin (SE Spain)
Water 2017, 9(2), 149; doi:10.3390/w9020149
Received: 9 January 2017 / Revised: 9 February 2017 / Accepted: 17 February 2017 / Published: 22 February 2017
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Abstract
The Segura River Basin is one of the most water-stressed basins in Mediterranean Europe. If we add to the actual situation that most climate change projections forecast important decreases in water resource availability in the Mediterranean region, the situation will become totally unsustainable.
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The Segura River Basin is one of the most water-stressed basins in Mediterranean Europe. If we add to the actual situation that most climate change projections forecast important decreases in water resource availability in the Mediterranean region, the situation will become totally unsustainable. This study assessed the impact of climate change in the headwaters of the Segura River Basin using the Soil and Water Assessment Tool (SWAT) with bias-corrected precipitation and temperature data from two Regional Climate Models (RCMs) for the medium term (2041–2070) and the long term (2071–2100) under two emission scenarios (RCP4.5 and RCP8.5). Bias correction was performed using the distribution mapping approach. The fuzzy TOPSIS technique was applied to rank a set of nine GCM–RCM combinations, choosing the climate models with a higher relative closeness. The study results show that the SWAT performed satisfactorily for both calibration (NSE = 0.80) and validation (NSE = 0.77) periods. Comparing the long-term and baseline (1971–2000) periods, precipitation showed a negative trend between 6% and 32%, whereas projected annual mean temperatures demonstrated an estimated increase of 1.5–3.3 °C. Water resources were estimated to experience a decrease of 2%–54%. These findings provide local water management authorities with very useful information in the face of climate change. Full article
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Open AccessArticle Simulating Spawning and Juvenile Rainbow Trout (Oncorhynchus mykiss) Habitat in Colorado River Based on High-Flow Effects
Water 2017, 9(2), 150; doi:10.3390/w9020150
Received: 8 December 2016 / Revised: 1 February 2017 / Accepted: 10 February 2017 / Published: 22 February 2017
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Abstract
High flow generates significant alterations in downstream river reaches, resulting in physical condition changes in the downstream regions of the river such as water depth, flow velocity, water temperature and river bed. These alterations will lead to change in fish habitat configuration in
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High flow generates significant alterations in downstream river reaches, resulting in physical condition changes in the downstream regions of the river such as water depth, flow velocity, water temperature and river bed. These alterations will lead to change in fish habitat configuration in the river. This paper proposes a model system to evaluate the high flow effects on river velocity, water depth, substrates changes, temperature distribution and consequently assess the change in spawning and juvenile rainbow trout (Oncorhynchus mykiss) habitats in the downstream region of the Glen Canyon Dam. Firstly, based on the 2 dimensional (2D) depth-averaged CFD (Computational Fluid Dynamics) model and heat transfer equation applied for simulation, three indices were simulated, namely depth, flow velocity and temperature distribution. Then, the spawning and juvenile fish preference curves were obtained based on these three indices and substrates distribution. After that, the habitat model was proposed and used to simulate the high flow effects on juvenile and spawning rainbow trout habitat structure. Finally, the weighted usable area (WUA) and overall suitability index (OSI) of the spawning and juvenile fish species were quantitatively simulated to estimate the habitat sensitivity. The results illustrate that the high flow effect (HFE) increased the juvenile rainbow trout habitat quality but decreased the spawning rainbow trout habitat quality. The juvenile trout were mainly affected by the water depth while the spawning rainbow trout were dominated by the bed elevation. Full article
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Open AccessReview Recent Advances in the Use of Chemical Markers for Tracing Wastewater Contamination in Aquatic Environment: A Review
Water 2017, 9(2), 143; doi:10.3390/w9020143
Received: 15 July 2016 / Accepted: 3 February 2017 / Published: 21 February 2017
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Abstract
There has been increasing research focus on the detection and occurrence of wastewater contamination in aquatic environment. Wastewater treatment plants receive effluents containing various chemical pollutants. These chemicals may not be fully removed during treatment and could potentially enter the receiving water bodies.
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There has been increasing research focus on the detection and occurrence of wastewater contamination in aquatic environment. Wastewater treatment plants receive effluents containing various chemical pollutants. These chemicals may not be fully removed during treatment and could potentially enter the receiving water bodies. Detection of these chemical pollutants and source identification could be a challenging research task due to the diversified chemical and functional groups, concentration levels and fate and transportation mechanisms of these pollutants in the environment. Chemical markers such as pharmaceuticals and personal care products, artificial sweeteners, fluorescent whitening agents, sterols and stanols, and nitrate and nitrogen isotopics have been widely used by most research as markers. These markers served as indicators of wastewater contamination to the receiving bodies due to their frequent usage, resistance to biodegradability and, more importantly, anthropogenic origin. These markers are commonly used in combination to identify the contaminant source of different origins. This article discusses the main chemical markers that are used to identify wastewater contamination in receiving bodies, the current trends, and approach to select suitable chemical markers. Full article
(This article belongs to the Special Issue Emerging Contaminants: Occurrence, Fate and Transport, and Removal)
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